User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0 Build ID: 20150508094354 Steps to reproduce: After Firefox updated to version 38 I began to notice YouTube videos becoming out of sync with the audio after about 8 minutes. Pausing and resuming the video did not resolve the problem. Refreshing the page and skipping to the forward to where I left off puts the audio and video back in sync. Skipping back 10 seconds with the J key also re-syncs the audio and video. Actual results: The audio and video become noticeably out of sync after about 8 minutes of playback on long videos. If a video is very long, after re-syncing the audio in the steps above, it will become out of sync again after another 8 minutes passes. Expected results: The audio and video shouldn't get out of sync. This problem did not occur prior to updating to Firefox 38.

Please post your about:support info. Is this any video or a specific one?

It only seems to do it with HTML5 videos. I installed a plugin called YouTube Flash Video Player, which lets you switch YouTube back to using the Flash player and it doesn't lose sync while using the Flash player. My about:support: Application Basics ------------------ Name: Firefox Version: 38.0.1 Build ID: 20150513174244 Update Channel: release User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0 Multiprocess Windows: 0/1 (default: false) Crash Reports for the Last 3 Days --------------------------------- All Crash Reports Extensions ---------- Name: Adblock Plus Version: 2.6.9 Enabled: true ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d} Name: BetterPrivacy Version: 1.68 Enabled: true ID: {d40f5e7b-d2cf-4856-b441-cc613eeffbe3} Name: ChatZilla Version: 0.9.91.1 Enabled: true ID: {59c81df5-4b7a-477b-912d-4e0fdf64e5f2} Name: DownThemAll! Version: 2.0.18 Enabled: true ID: {DDC359D1-844A-42a7-9AA1-88A850A938A8} Name: Enhanced Steam Version: 7.3 Enabled: true ID: jid1-YdiFiTEkQgInxA@jetpack Name: FoxBleed Version: 0.1 Enabled: true ID: jid1-Ni8A2ixlGmYBiw@jetpack Name: Ghostery Version: 5.4.5 Enabled: true ID: firefox@ghostery.com Name: Greasemonkey Version: 3.1 Enabled: true ID: {e4a8a97b-f2ed-450b-b12d-ee082ba24781} Name: Hover Hound Version: 1.4.3 Enabled: true ID: jid0-PEBvWWKP6g5gzvk2gsdrh097hv0@jetpack Name: HTTPS-Everywhere Version: 5.0.4 Enabled: true ID: https-everywhere@eff.org Name: Self-Destructing Cookies Version: 0.4.7 Enabled: true ID: jid0-9XfBwUWnvPx4wWsfBWMCm4Jj69E@jetpack Name: YouTube Flash Video Player Version: 37.0 Enabled: false ID: {f3bd3dd2-2888-44c5-91a2-2caeb33fb898} Graphics -------- Adapter Description: NVIDIA GeForce GTX 970 Adapter Drivers: nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Adapter RAM: 4095 ClearType Parameters: D [ Gamma: 2200 Pixel Structure: R ClearType Level: 50 Enhanced Contrast: 0 ] D [ Gamma: 2200 Pixel Structure: R ClearType Level: 100 Enhanced Contrast: 100 ] Device ID: 0x13c2 Direct2D Enabled: true DirectWrite Enabled: true (6.1.7601.18834) Driver Date: 4-8-2015 Driver Version: 9.18.13.5012 GPU #2 Active: false GPU Accelerated Windows: 1/1 Direct3D 11 (OMTC) Subsys ID: 29783842 Vendor ID: 0x10de WebGL Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GTX 970 Direct3D9Ex vs_3_0 ps_3_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d AzureContentBackend: direct2d AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0 Important Modified Preferences ------------------------------ accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 51200 browser.cache.disk.smart_size_cached_value: 1048576 browser.cache.disk.smart_size.enabled: false browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.frecency_experiment: 2 browser.download.importedFromSqlite: true browser.places.smartBookmarksVersion: 7 browser.search.useDBForOrder: true browser.sessionstore.upgradeBackup.latestBuildID: 20150513174244 browser.startup.homepage: https://www.google.com/ browser.startup.homepage_override.buildID: 20150513174244 browser.startup.homepage_override.mstone: 38.0.1 browser.tabs.closeButtons: 0 browser.tabs.drawInTitlebar: false dom.mozApps.used: true dom.w3c_touch_events.expose: false extensions.lastAppVersion: 38.0.1 font.internaluseonly.changed: false gfx.direct3d.last_used_feature_level_idx: 0 gfx.direct3d.prefer_10_1: true javascript.options.showInConsole: false media.eme.enabled: false media.gmp-gmpopenh264.lastUpdate: 1431499907 media.gmp-gmpopenh264.version: 1.4 media.gmp-manager.buildID: 20150513174244 media.gmp-manager.lastCheck: 1431918225 network.cookie.prefsMigrated: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1431932171 places.history.expiration.transient_current_max_pages: 104858 places.history.expiration.transient_optimal_database_size: 167772160 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true plugin.state.flash: 1 plugin.state.np32dsw: 1 plugin.state.npunity3d: 1 print.print_printer: Samsung SCX-4100 Series print.printer_Microsoft_XPS_Document_Writer.print_bgcolor: false print.printer_Microsoft_XPS_Document_Writer.print_bgimages: false print.printer_Microsoft_XPS_Document_Writer.print_colorspace: print.printer_Microsoft_XPS_Document_Writer.print_command: print.printer_Microsoft_XPS_Document_Writer.print_downloadfonts: false print.printer_Microsoft_XPS_Document_Writer.print_duplex: 0 print.printer_Microsoft_XPS_Document_Writer.print_edge_bottom: 0 print.printer_Microsoft_XPS_Document_Writer.print_edge_left: 0 print.printer_Microsoft_XPS_Document_Writer.print_edge_right: 0 print.printer_Microsoft_XPS_Document_Writer.print_edge_top: 0 print.printer_Microsoft_XPS_Document_Writer.print_evenpages: true print.printer_Microsoft_XPS_Document_Writer.print_footercenter: &U print.printer_Microsoft_XPS_Document_Writer.print_footerleft: print.printer_Microsoft_XPS_Document_Writer.print_footerright: print.printer_Microsoft_XPS_Document_Writer.print_headercenter: print.printer_Microsoft_XPS_Document_Writer.print_headerleft: print.printer_Microsoft_XPS_Document_Writer.print_headerright: print.printer_Microsoft_XPS_Document_Writer.print_in_color: true print.printer_Microsoft_XPS_Document_Writer.print_margin_bottom: 0.5 print.printer_Microsoft_XPS_Document_Writer.print_margin_left: 0.5 print.printer_Microsoft_XPS_Document_Writer.print_margin_right: 0.5 print.printer_Microsoft_XPS_Document_Writer.print_margin_top: 0.5 print.printer_Microsoft_XPS_Document_Writer.print_oddpages: true print.printer_Microsoft_XPS_Document_Writer.print_orientation: 0 print.printer_Microsoft_XPS_Document_Writer.print_page_delay: 50 print.printer_Microsoft_XPS_Document_Writer.print_paper_data: 1 print.printer_Microsoft_XPS_Document_Writer.print_paper_height: 11.00 print.printer_Microsoft_XPS_Document_Writer.print_paper_name: print.printer_Microsoft_XPS_Document_Writer.print_paper_size_type: 0 print.printer_Microsoft_XPS_Document_Writer.print_paper_size_unit: 0 print.printer_Microsoft_XPS_Document_Writer.print_paper_width: 8.50 print.printer_Microsoft_XPS_Document_Writer.print_plex_name: print.printer_Microsoft_XPS_Document_Writer.print_resolution: 0 print.printer_Microsoft_XPS_Document_Writer.print_resolution_name: print.printer_Microsoft_XPS_Document_Writer.print_reversed: false print.printer_Microsoft_XPS_Document_Writer.print_scaling: 1.00 print.printer_Microsoft_XPS_Document_Writer.print_shrink_to_fit: true print.printer_Microsoft_XPS_Document_Writer.print_to_file: false print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_bottom: 0 print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_left: 0 print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_right: 0 print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_top: 0 print.printer_Samsung_SCX-4100_Series.print_bgcolor: false print.printer_Samsung_SCX-4100_Series.print_bgimages: false print.printer_Samsung_SCX-4100_Series.print_command: print.printer_Samsung_SCX-4100_Series.print_downloadfonts: false print.printer_Samsung_SCX-4100_Series.print_edge_bottom: 0 print.printer_Samsung_SCX-4100_Series.print_edge_left: 0 print.printer_Samsung_SCX-4100_Series.print_edge_right: 0 print.printer_Samsung_SCX-4100_Series.print_edge_top: 0 print.printer_Samsung_SCX-4100_Series.print_evenpages: true print.printer_Samsung_SCX-4100_Series.print_footercenter: print.printer_Samsung_SCX-4100_Series.print_footerleft: &U print.printer_Samsung_SCX-4100_Series.print_footerright: print.printer_Samsung_SCX-4100_Series.print_headercenter: print.printer_Samsung_SCX-4100_Series.print_headerleft: &PT print.printer_Samsung_SCX-4100_Series.print_headerright: print.printer_Samsung_SCX-4100_Series.print_in_color: true print.printer_Samsung_SCX-4100_Series.print_margin_bottom: 0.5 print.printer_Samsung_SCX-4100_Series.print_margin_left: 0.5 print.printer_Samsung_SCX-4100_Series.print_margin_right: 0.5 print.printer_Samsung_SCX-4100_Series.print_margin_top: 0.5 print.printer_Samsung_SCX-4100_Series.print_oddpages: true print.printer_Samsung_SCX-4100_Series.print_orientation: 0 print.printer_Samsung_SCX-4100_Series.print_page_delay: 50 print.printer_Samsung_SCX-4100_Series.print_paper_data: 1 print.printer_Samsung_SCX-4100_Series.print_paper_height: 11.00 print.printer_Samsung_SCX-4100_Series.print_paper_size_type: 0 print.printer_Samsung_SCX-4100_Series.print_paper_size_unit: 0 print.printer_Samsung_SCX-4100_Series.print_paper_width: 8.50 print.printer_Samsung_SCX-4100_Series.print_reversed: false print.printer_Samsung_SCX-4100_Series.print_scaling: 1.00 print.printer_Samsung_SCX-4100_Series.print_shrink_to_fit: true print.printer_Samsung_SCX-4100_Series.print_to_file: false print.printer_Samsung_SCX-4100_Series.print_unwriteable_margin_bottom: 0 print.printer_Samsung_SCX-4100_Series.print_unwriteable_margin_left: 0 print.printer_Samsung_SCX-4100_Series.print_unwriteable_margin_right: 0 print.printer_Samsung_SCX-4100_Series.print_unwriteable_margin_top: 0 privacy.cpd.extensions-betterprivacy: true privacy.cpd.extensions-dta: true privacy.cpd.offlineApps: true privacy.cpd.siteSettings: true privacy.donottrackheader.enabled: true privacy.donottrackheader.value: 1 privacy.sanitize.migrateFx3Prefs: true privacy.sanitize.timeSpan: 0 security.tls.version.max: 1 security.warn_viewing_mixed: false storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1431506845 Important Locked Preferences ---------------------------- JavaScript ---------- Incremental GC: true Accessibility ------------- Activated: false Prevent Accessibility: 0 Library Versions ---------------- NSPR Expected minimum version: 4.10.8 Version in use: 4.10.8 NSS Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSSMIME Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSSSL Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSUTIL Expected minimum version: 3.18.1 Version in use: 3.18.1 Experimental Features ---------------------

Chris any ideas?

Jim: does this audio problem happen for all videos over 8 minutes? If it happens for specific videos, can you share a link? You might try flipping your "media.hardware-video-decoding.enabled" or ("media.windows-media-foundation.use-dxva" about:config prefs to false. Maybe Firefox's software audio decoding is out of sync with the GPU video decoding. This sounds like an MSE bug. MSE was enabled intermittently during Firefox 37, but Firefox 38 was when YouTube turned it on for all Windows Vista+ users. Anthony: do you know of any MSE audio sync bugs in Firefox 38?

It may be related to bug 1136360.

Yes it happens on all long videos. The audio doesn't suddenly go out of sync at 8 minutes, it gradually goes out of sync and becomes noticeable around 8 minutes, though now that I'm aware of it I notice it as early as 5-6 minutes. I've only noticed it on YouTube, though I don't think I've watched any videos recently on other video services that use HTML5 video players. I looked in about:config and I didn't have a "media.hardware-video-decoding.enabled" option, but I did have "media.windows-media-foundation.use-dxva" which I toggled to false. It didn't have any effect though. I tried starting in safe mode, which didn't work, so I created a new clean profile and that also didn't work. Here is the about:support from the new, clean profile: Application Basics ------------------ Name: Firefox Version: 38.0.1 Build ID: 20150513174244 Update Channel: release User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0 Multiprocess Windows: 0/1 (default: false) Crash Reports for the Last 3 Days --------------------------------- All Crash Reports Extensions ---------- Graphics -------- Adapter Description: NVIDIA GeForce GTX 970 Adapter Drivers: nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Adapter RAM: 4095 ClearType Parameters: D [ Gamma: 2200 Pixel Structure: R ClearType Level: 50 Enhanced Contrast: 0 ] D [ Gamma: 2200 Pixel Structure: R ClearType Level: 100 Enhanced Contrast: 100 ] Device ID: 0x13c2 Direct2D Enabled: true DirectWrite Enabled: true (6.1.7601.18834) Driver Date: 4-8-2015 Driver Version: 9.18.13.5012 GPU #2 Active: false GPU Accelerated Windows: 1/1 Direct3D 11 (OMTC) Subsys ID: 29783842 Vendor ID: 0x10de WebGL Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GTX 970 Direct3D9Ex vs_3_0 ps_3_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d AzureContentBackend: direct2d AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0 Important Modified Preferences ------------------------------ browser.cache.disk.capacity: 358400 browser.cache.disk.smart_size.first_run: false browser.cache.frecency_experiment: 3 browser.download.importedFromSqlite: true browser.places.smartBookmarksVersion: 7 browser.startup.homepage_override.buildID: 20150513174244 browser.startup.homepage_override.mstone: 38.0.1 extensions.lastAppVersion: 38.0.1 gfx.direct3d.last_used_feature_level_idx: 0 media.gmp-eme-adobe.lastUpdate: 1432032646 media.gmp-eme-adobe.version: 9 media.gmp-gmpopenh264.lastUpdate: 1432032646 media.gmp-gmpopenh264.version: 1.4 media.gmp-manager.buildID: 20150513174244 media.gmp-manager.lastCheck: 1432032643 network.cookie.prefsMigrated: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1432033008 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true plugin.state.flash: 1 plugin.state.npunity3d: 1 privacy.sanitize.migrateFx3Prefs: true storage.vacuum.last.index: 0 storage.vacuum.last.places.sqlite: 1432033008 Important Locked Preferences ---------------------------- JavaScript ---------- Incremental GC: true Accessibility ------------- Activated: false Prevent Accessibility: 0 Library Versions ---------------- NSPR Expected minimum version: 4.10.8 Version in use: 4.10.8 NSS Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSSMIME Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSSSL Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSUTIL Expected minimum version: 3.18.1 Version in use: 3.18.1 Experimental Features ---------------------

I have exactly the same problem. It started to happen with Firefox 38.0, 38.0.1 didn't fix it. Using the HTML5 YouTube player on Firefox 37 did NOT show that bug. Contary to Jim I am using Windows 8.1 x64, but I also have an Nvidia card (although a different one) with the newest driver. I am using a Creative card for audio, if that information also helps. Here is my about:support (it's in German, I hope that's not a problem): Allgemeine Informationen ------------------------ Name: Firefox Version: 38.0.1 Build-ID: 20150513174244 Update-Kanal: release User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0 Fenster mit mehreren Prozessen: 0/1 (Standard: false) Absturzberichte der letzten 3 Tage ---------------------------------- Alle Absturzberichte Erweiterungen ------------- Name: Adblock Plus Version: 2.6.9 Aktiviert: true ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d} Name: Flagfox Version: 5.0.15 Aktiviert: true ID: {1018e4d6-728f-4b20-ad56-37578a4de76b} Name: Greasemonkey Version: 3.1 Aktiviert: true ID: {e4a8a97b-f2ed-450b-b12d-ee082ba24781} Name: HTTPS-Everywhere Version: 5.0.4 Aktiviert: true ID: https-everywhere@eff.org Name: RefControl Version: 0.8.17 Aktiviert: true ID: {455D905A-D37C-4643-A9E2-F6FEFAA0424A} Name: Smartest Bookmarks Bar Version: 1.11 Aktiviert: true ID: {b442f4c0-c292-4998-aabe-48608a73ba75} Name: Tab Wheel Scroll Version: 20140723 Aktiviert: true ID: tabscroll@mthamil Name: YouTube High Definition Version: 37.1 Aktiviert: true ID: {7b1bf0b6-a1b9-42b0-b75d-252036438bdc} Name: Video DownloadHelper Version: 5.2.0 Aktiviert: false ID: {b9db16a4-6edc-47ec-a1f4-b86292ed211d} Grafik ------ Direct2D aktiviert: true DirectWrite aktiviert: true (6.3.9600.17795) Geräte-ID: 0x1183 GPU #2 aktiv: false GPU-beschleunigte Fenster: 1/1 Direct3D 11 (OMTC) Karten-Beschreibung: NVIDIA GeForce GTX 660 Ti Karten-RAM: 2048 Karten-Treiber: nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Subsys-ID: 00000000 Treiber-Datum: 5-11-2015 Treiber-Version: 9.18.13.5286 Vendor-ID: 0x10de WebGL-Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GTX 660 Ti Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d 1.1 AzureContentBackend: direct2d 1.1 AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0 Wichtige modifizierte Einstellungen ----------------------------------- accessibility.blockautorefresh: true accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 358400 browser.cache.disk.smart_size_cached_value: 358400 browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.frecency_experiment: 2 browser.download.folderList: 2 browser.download.importedFromSqlite: true browser.places.smartBookmarksVersion: 7 browser.search.useDBForOrder: true browser.sessionstore.upgradeBackup.latestBuildID: 20150513174244 browser.startup.homepage: **REMOVED** browser.startup.homepage_override.buildID: 20150513174244 browser.startup.homepage_override.mstone: 38.0.1 browser.tabs.warnOnClose: false dom.mozApps.used: true dom.w3c_touch_events.expose: false extensions.lastAppVersion: 38.0.1 font.internaluseonly.changed: true gfx.direct3d.checkDX10: true gfx.direct3d.last_used_feature_level_idx: 0 gfx.direct3d.prefer_10_1: true media.eme.enabled: false media.gmp-gmpopenh264.lastUpdate: 1431462094 media.gmp-gmpopenh264.version: 1.4 media.gmp-manager.buildID: 20150513174244 media.gmp-manager.lastCheck: 1431955849 network.cookie.cookieBehavior: 1 network.cookie.lifetimePolicy: 2 network.cookie.prefsMigrated: true network.dns.disablePrefetch: true network.predictor.cleaned-up: true network.prefetch-next: false places.database.lastMaintenance: 1431982044 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true plugin.state.npadobeaamdetect: 0 plugin.state.npmeetingjoinpluginoc: 0 plugin.state.nppdf: 0 plugin.state.npspwrap: 0 privacy.clearOnShutdown.cookies: false privacy.clearOnShutdown.downloads: false privacy.clearOnShutdown.history: false privacy.clearOnShutdown.offlineApps: true privacy.clearOnShutdown.passwords: true privacy.donottrackheader.enabled: true privacy.sanitize.migrateFx3Prefs: true privacy.sanitize.sanitizeOnShutdown: true security.disable_button.openCertManager: false security.disable_button.openDeviceManager: false storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1431462453 Wichtige nicht veränderbare Einstellungen ----------------------------------------- JavaScript ---------- Inkrementelle GC: true Barrierefreiheit ---------------- Aktiviert: false Barrierefreiheit verhindern: 0 Bibliotheken-Versionen ---------------------- NSPR Minimal vorausgesetzte Version: 4.10.8 Verwendete Version: 4.10.8 NSS Minimal vorausgesetzte Version: 3.18.1 Basic ECC Verwendete Version: 3.18.1 Basic ECC NSSSMIME Minimal vorausgesetzte Version: 3.18.1 Basic ECC Verwendete Version: 3.18.1 Basic ECC NSSSSL Minimal vorausgesetzte Version: 3.18.1 Basic ECC Verwendete Version: 3.18.1 Basic ECC NSSUTIL Minimal vorausgesetzte Version: 3.18.1 Verwendete Version: 3.18.1 Experimentelle Funktionen -------------------------

Can confirm, v37 was perfect, 38 broke something. Seems to only happen to sub 60fps videos though. Have yes to see out of sync 60fps one. As for example video it happens and easy to see http://www.youtube.com/watch?v=xrsUMEbLtOs Support info (Browser is Waterfox 38): Application Basics ------------------ Name: Firefox Version: 38.0 Build ID: 20150512005755 Update Channel: release User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:38.0) Gecko/20100101 Firefox/38.0 Multiprocess Windows: 0/1 (default: false) Crash Reports for the Last 3 Days --------------------------------- All Crash Reports Extensions ---------- Name: Add to Search Bar Version: 2.8 Enabled: true ID: add-to-searchbox@maltekraus.de Name: All-in-One Sidebar Version: 0.7.25 Enabled: true ID: {097d3191-e6fa-4728-9826-b533d755359d} Name: Classic Theme Restorer Version: 1.3.2 Enabled: true ID: ClassicThemeRestorer@ArisT2Noia4dev Name: Context Search Version: 0.6.3 Enabled: true ID: {902D2C4A-457A-4EF9-AD43-7014562929FF} Name: Custom Buttons Version: 0.0.5.8 Enabled: true ID: custombuttons@xsms.org Name: Enhanced Steam Version: 5.9.1 Enabled: true ID: jid0-SmvlvxGpvCyG252KbVMqIKR79Uc@jetpack Name: Fast Dial Version: 4.12 Enabled: true ID: fastdial@telega.phpnet.us Name: Feed Sidebar Version: 8.0.4 Enabled: true ID: feedbar@efinke.com Name: Google Image Search Version: 1.15 Enabled: true ID: {73007fef-a6e0-47d3-b4e7-dfc116ed6f65} Name: GPU Accelerated Flash Player Version: 1.32 Enabled: true ID: gpuacceleratedflashplayer@stas Name: Greasemonkey Version: 3.1 Enabled: true ID: {e4a8a97b-f2ed-450b-b12d-ee082ba24781} Name: HDS Link Detector Version: 0.6 Enabled: true ID: jid0-HFFmJoceGjTSKDBEWPpzfX9By7I@jetpack Name: Mozilla Archive Format Version: 3.1.0 Enabled: true ID: {7f57cf46-4467-4c2d-adfa-0cba7c507e54} Name: Nimbus Screen Capture - editable screenshots. Version: 6.4.1 Enabled: true ID: nimbusscreencaptureff@everhelper.me Name: Reddit Enhancement Suite Version: 4.5.4.1-signed Enabled: true ID: jid1-xUfzOsOFlzSOXg@jetpack Name: Tab Mix Plus Version: 0.4.1.7 Enabled: true ID: {dc572301-7619-498c-a57d-39143191b318} Name: uBlock₀ Version: 0.9.3.1 Enabled: true ID: {2b10c1c8-a11f-4bad-fe9c-1c11e82cac42} Name: YouTube Center Developer Build Version: 525 Enabled: true ID: jid1-cwbvBTE216jjpg@jetpack Name: Adblock Edge Version: 2.1.9 Enabled: false ID: {fe272bd1-5f76-4ea4-8501-a05d35d823fc} Name: Awesome screenshot: Capture and Annotate Version: 2.4.9 Enabled: false ID: jid0-GXjLLfbCoAx0LcltEdFrEkQdQPI@jetpack Name: Exif Viewer Version: 2.00 Enabled: false ID: exif_viewer@mozilla.doslash.org Name: h264ify Version: 1.0.0 Enabled: false ID: jid1-TSgSxBhncsPBWQ@jetpack Name: Hola Better Internet Version: 1.7.824 Enabled: false ID: jid1-4P0kohSJxU1qGg@jetpack Name: OmniSidebar Version: 1.5.4 Enabled: false ID: osb@quicksaver Name: Reddited Version: 2.0 Enabled: false ID: jid1-o6Fu4SiUcHDCsw@jetpack Name: RuCrash Extension Version: 1.0 Enabled: false ID: {54A49BCD-E2F2-4E06-B165-D29BF3E8BE00} Name: Transmogrify for Plex Version: 1.3.4 Enabled: false ID: transmogrifyforplex@moussekateer Name: YouTube Enhancer Plus Version: 3.3.6 Enabled: false ID: firefoxaddon@youtubeenhancer.com Graphics -------- Adapter Description: NVIDIA GeForce GTX 780 Adapter Drivers: nvd3dumx,nvwgf2umx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um,nvwgf2um Adapter RAM: 3072 Device ID: 0x1004 Direct2D Enabled: true DirectWrite Enabled: true (10.0.10074.0) Driver Date: 5-10-2015 Driver Version: 9.18.13.5284 GPU #2 Active: false GPU Accelerated Windows: 1/1 Direct3D 11 (OMTC) Subsys ID: 10041569 Vendor ID: 0x10de WebGL Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GTX 780 Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d 1.1 AzureContentBackend: direct2d 1.1 AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0 Important Modified Preferences ------------------------------ accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 358400 browser.cache.disk.smart_size_cached_value: 358400 browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.frecency_experiment: 4 browser.download.folderList: 2 browser.download.importedFromSqlite: true browser.download.manager.alertOnEXEOpen: false browser.download.manager.showWhenStarting: false browser.download.useDownloadDir: false browser.link.open_newwindow.override.external: 3 browser.places.smartBookmarksVersion: 7 browser.search.useDBForOrder: true browser.sessionstore.max_tabs_undo: 20 browser.sessionstore.upgradeBackup.latestBuildID: 20150511212419 browser.startup.homepage_override.buildID: 20150511212419 browser.startup.homepage_override.mstone: 38.0 browser.tabs.closeWindowWithLastTab: false browser.tabs.selectOwnerOnClose: false browser.tabs.tabMaxWidth: 176 browser.tabs.tabMinWidth: 30 browser.tabs.warnOnClose: false dom.mozApps.used: true extensions.lastAppVersion: 38.0 font.internaluseonly.changed: true gfx.direct3d.last_used_feature_level_idx: 0 media.gmp-gmpopenh264.lastUpdate: 1431620393 media.gmp-gmpopenh264.version: 1.4 media.gmp-manager.buildID: 20150511212419 media.gmp-manager.lastCheck: 1432042962 media.mediasource.webm.enabled: false mousewheel.default.delta_multiplier_y: 300 network.cookie.prefsMigrated: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1431688323 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true print.printer_Canon_MG3500_series_Printer.print_bgcolor: false print.printer_Canon_MG3500_series_Printer.print_bgimages: false print.printer_Canon_MG3500_series_Printer.print_colorspace: print.printer_Canon_MG3500_series_Printer.print_command: print.printer_Canon_MG3500_series_Printer.print_downloadfonts: false print.printer_Canon_MG3500_series_Printer.print_duplex: 1515870810 print.printer_Canon_MG3500_series_Printer.print_edge_bottom: 0 print.printer_Canon_MG3500_series_Printer.print_edge_left: 0 print.printer_Canon_MG3500_series_Printer.print_edge_right: 0 print.printer_Canon_MG3500_series_Printer.print_edge_top: 0 print.printer_Canon_MG3500_series_Printer.print_evenpages: true print.printer_Canon_MG3500_series_Printer.print_footercenter: print.printer_Canon_MG3500_series_Printer.print_footerleft: &PT print.printer_Canon_MG3500_series_Printer.print_footerright: &D print.printer_Canon_MG3500_series_Printer.print_headercenter: print.printer_Canon_MG3500_series_Printer.print_headerleft: &T print.printer_Canon_MG3500_series_Printer.print_headerright: &U print.printer_Canon_MG3500_series_Printer.print_in_color: true print.printer_Canon_MG3500_series_Printer.print_margin_bottom: 0.5 print.printer_Canon_MG3500_series_Printer.print_margin_left: 0.5 print.printer_Canon_MG3500_series_Printer.print_margin_right: 0.5 print.printer_Canon_MG3500_series_Printer.print_margin_top: 0.5 print.printer_Canon_MG3500_series_Printer.print_oddpages: true print.printer_Canon_MG3500_series_Printer.print_orientation: 0 print.printer_Canon_MG3500_series_Printer.print_page_delay: 50 print.printer_Canon_MG3500_series_Printer.print_paper_data: 9 print.printer_Canon_MG3500_series_Printer.print_paper_height: 11,00 print.printer_Canon_MG3500_series_Printer.print_paper_name: print.printer_Canon_MG3500_series_Printer.print_paper_size_type: 0 print.printer_Canon_MG3500_series_Printer.print_paper_size_unit: 1 print.printer_Canon_MG3500_series_Printer.print_paper_width: 8,50 print.printer_Canon_MG3500_series_Printer.print_plex_name: print.printer_Canon_MG3500_series_Printer.print_resolution: 1515870810 print.printer_Canon_MG3500_series_Printer.print_resolution_name: print.printer_Canon_MG3500_series_Printer.print_reversed: false print.printer_Canon_MG3500_series_Printer.print_scaling: 1,00 print.printer_Canon_MG3500_series_Printer.print_shrink_to_fit: true print.printer_Canon_MG3500_series_Printer.print_to_file: false print.printer_Canon_MG3500_series_Printer.print_unwriteable_margin_bottom: 0 print.printer_Canon_MG3500_series_Printer.print_unwriteable_margin_left: 0 print.printer_Canon_MG3500_series_Printer.print_unwriteable_margin_right: 0 print.printer_Canon_MG3500_series_Printer.print_unwriteable_margin_top: 0 privacy.sanitize.migrateFx3Prefs: true storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1431011155 webgl.force-enabled: true Important Locked Preferences ---------------------------- JavaScript ---------- Incremental GC: true Accessibility ------------- Activated: false Prevent Accessibility: 0 Library Versions ---------------- NSPR Expected minimum version: 4.10.8 Version in use: 4.10.8 NSS Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSSMIME Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSSSL Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSUTIL Expected minimum version: 3.18.1 Version in use: 3.18.1 Experimental Features ---------------------

This still happens with Firefox 38.0.5 released today.

Can confirm, this happens on 38.0.5.

Confirming what the other two comments are saying. Still happens for long videos. Here's an additional about:support for 38.0.5 Application Basics ------------------ Name: Firefox Version: 38.0.5 Build ID: 20150525141253 Update Channel: release User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0 Multiprocess Windows: 0/1 (default: false) Crash Reports for the Last 3 Days --------------------------------- All Crash Reports Extensions -------------------------------- Name: Adblock Plus Version: 2.6.9.1-signed Enabled: true ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d} Name: Adobe Acrobat - Create PDF Version: 1.2 Enabled: true ID: web2pdfextension@web2pdf.adobedotcom Name: BetterTTV Version: 6.6 Enabled: true ID: jid0-OeCFXKAPh2tC0bN3Li9ajRAZx6c@jetpack Name: Brief Version: 2.0b3 Enabled: true ID: brief@mozdev.org Name: Flagfox Version: 5.1.0 Enabled: true ID: {1018e4d6-728f-4b20-ad56-37578a4de76b} Name: Google Similar Images Version: 0.5.1-signed Enabled: true ID: nishan.naseer.googimagesearch@gmail.com Name: Greasemonkey Version: 3.2 Enabled: true ID: {e4a8a97b-f2ed-450b-b12d-ee082ba24781} Name: IDM CC Version: 7.3.100 Enabled: true ID: mozilla_cc@internetdownloadmanager.com Name: LastPass Version: 3.1.95 Enabled: true ID: support@lastpass.com Name: MEGA Version: 2.0.223 Enabled: true ID: firefox@mega.co.nz Name: NoScript Version: 2.6.9.26 Enabled: true ID: {73a6fe31-595d-460b-a920-fcc0f8843232} Name: Reddit Enhancement Suite Version: 4.5.4.1-signed Enabled: true ID: jid1-xUfzOsOFlzSOXg@jetpack Name: Rikaichan Version: 2.09.1-signed Enabled: true ID: {0AA9101C-D3C1-4129-A9B7-D778C6A17F82} Name: Rikaichan Japanese Names Dictionary File Version: 2.01.150401 Enabled: true ID: rikaichan-jpnames@polarcloud.com Name: Rikaichan Japanese-English Dictionary File Version: 2.01.150401 Enabled: true ID: rikaichan-jpen@polarcloud.com Name: Save Image in Folder Version: 1.3.16.1-signed Enabled: true ID: {5e594888-3e8e-47da-b2c6-b0b545112f84} Name: Twitter App Version: 38.0-signed Enabled: true ID: {12b6fdcd-4423-4276-82a3-73fdbff5f7e4} Name: Xmarks Version: 4.3.7 Enabled: true ID: foxmarks@kei.com Graphics -------- Adapter Description: NVIDIA GeForce GTX 770 Adapter Drivers: nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Adapter RAM: 2048 Device ID: 0x1184 Direct2D Enabled: true DirectWrite Enabled: true (6.2.9200.17292) Driver Date: 5-11-2015 Driver Version: 9.18.13.5286 GPU #2 Active: false GPU Accelerated Windows: 1/1 Direct3D 11 (OMTC) Subsys ID: 36031458 Vendor ID: 0x10de WebGL Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GTX 770 Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d 1.1 AzureContentBackend: direct2d 1.1 AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0 (#0) Error: [D2D1.1] 4CreateBitmap failure Size(32,24914) Code: 0x80070057 (#8) Error: [D2D1.1] 4CreateBitmap failure Size(32,24914) Code: 0x80070057 (#9) Error: [D2D1.1] 4CreateBitmap failure Size(32,24914) Code: 0x80070057 (#10) Error: [D2D1.1] 4CreateBitmap failure Size(32,24914) Code: 0x80070057 (#11) Error: [D2D1.1] 4CreateBitmap failure Size(32,24914) Code: 0x80070057 (#12) Error: [D2D1.1] 4CreateBitmap failure Size(32,24914) Code: 0x80070057 Important Modified Preferences ------------------------------ accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 358400 browser.cache.disk.smart_size_cached_value: 358400 browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.frecency_experiment: 4 browser.download.importedFromSqlite: true browser.newtab.url: about:blank browser.places.smartBookmarksVersion: 7 browser.search.useDBForOrder: true browser.sessionstore.upgradeBackup.latestBuildID: 20150525141253 browser.startup.homepage_override.buildID: 20150525141253 browser.startup.homepage_override.mstone: 38.0.5 browser.tabs.onTop: false browser.tabs.warnOnClose: false dom.disable_open_during_load: false dom.max_chrome_script_run_time: 40 dom.max_script_run_time: 40 dom.mozApps.used: true extensions.lastAppVersion: 38.0.5 font.internaluseonly.changed: true gfx.direct3d.last_used_feature_level_idx: 0 media.gmp-eme-adobe.lastUpdate: 1433166577 media.gmp-eme-adobe.version: 10 media.gmp-gmpopenh264.lastUpdate: 1431823873 media.gmp-gmpopenh264.version: 1.4 media.gmp-manager.buildID: 20150525141253 media.gmp-manager.lastCheck: 1433995205 network.cookie.prefsMigrated: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1433944315 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true plugin.state.npvlc: 2 print.printer_EPSONA93529_(XP-410_Series).print_bgcolor: false print.printer_EPSONA93529_(XP-410_Series).print_bgimages: false print.printer_EPSONA93529_(XP-410_Series).print_colorspace: print.printer_EPSONA93529_(XP-410_Series).print_command: print.printer_EPSONA93529_(XP-410_Series).print_downloadfonts: false print.printer_EPSONA93529_(XP-410_Series).print_duplex: 4259908 print.printer_EPSONA93529_(XP-410_Series).print_edge_bottom: 0 print.printer_EPSONA93529_(XP-410_Series).print_edge_left: 0 print.printer_EPSONA93529_(XP-410_Series).print_edge_right: 0 print.printer_EPSONA93529_(XP-410_Series).print_edge_top: 0 print.printer_EPSONA93529_(XP-410_Series).print_evenpages: true print.printer_EPSONA93529_(XP-410_Series).print_footercenter: print.printer_EPSONA93529_(XP-410_Series).print_footerleft: &PT print.printer_EPSONA93529_(XP-410_Series).print_footerright: &D print.printer_EPSONA93529_(XP-410_Series).print_headercenter: print.printer_EPSONA93529_(XP-410_Series).print_headerleft: &T print.printer_EPSONA93529_(XP-410_Series).print_headerright: &U print.printer_EPSONA93529_(XP-410_Series).print_in_color: true print.printer_EPSONA93529_(XP-410_Series).print_margin_bottom: 0.5 print.printer_EPSONA93529_(XP-410_Series).print_margin_left: 0.5 print.printer_EPSONA93529_(XP-410_Series).print_margin_right: 0.5 print.printer_EPSONA93529_(XP-410_Series).print_margin_top: 0.5 print.printer_EPSONA93529_(XP-410_Series).print_oddpages: true print.printer_EPSONA93529_(XP-410_Series).print_orientation: 0 print.printer_EPSONA93529_(XP-410_Series).print_page_delay: 50 print.printer_EPSONA93529_(XP-410_Series).print_paper_data: 9 print.printer_EPSONA93529_(XP-410_Series).print_paper_height: 11.00 print.printer_EPSONA93529_(XP-410_Series).print_paper_name: print.printer_EPSONA93529_(XP-410_Series).print_paper_size_type: 0 print.printer_EPSONA93529_(XP-410_Series).print_paper_size_unit: 1 print.printer_EPSONA93529_(XP-410_Series).print_paper_width: 8.50 print.printer_EPSONA93529_(XP-410_Series).print_plex_name: print.printer_EPSONA93529_(XP-410_Series).print_resolution: 4784193 print.printer_EPSONA93529_(XP-410_Series).print_resolution_name: print.printer_EPSONA93529_(XP-410_Series).print_reversed: false print.printer_EPSONA93529_(XP-410_Series).print_scaling: 1.00 print.printer_EPSONA93529_(XP-410_Series).print_shrink_to_fit: true print.printer_EPSONA93529_(XP-410_Series).print_to_file: false print.printer_EPSONA93529_(XP-410_Series).print_unwriteable_margin_bottom: 0 print.printer_EPSONA93529_(XP-410_Series).print_unwriteable_margin_left: 0 print.printer_EPSONA93529_(XP-410_Series).print_unwriteable_margin_right: 0 print.printer_EPSONA93529_(XP-410_Series).print_unwriteable_margin_top: 0 privacy.clearOnShutdown.cookies: false privacy.clearOnShutdown.sessions: false privacy.sanitize.migrateFx3Prefs: true privacy.sanitize.sanitizeOnShutdown: true storage.vacuum.last.brief.sqlite: 1420558477 storage.vacuum.last.index: 2 storage.vacuum.last.places.sqlite: 1433388921 Important Locked Preferences ---------------------------- JavaScript ---------- Incremental GC: true Accessibility ------------- Activated: false Prevent Accessibility: 0 Library Versions ---------------- NSPR Expected minimum version: 4.10.8 Version in use: 4.10.8 NSS Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSSMIME Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSSSL Expected minimum version: 3.18.1 Basic ECC Version in use: 3.18.1 Basic ECC NSSUTIL Expected minimum version: 3.18.1 Version in use: 3.18.1 Experimental Features ---------------------

Still not working with Firefox 39.0

I have the same problem even with v39.0 Here is my about:support Application Basics ------------------ Name: Firefox Version: 39.0 Build ID: 20150630154324 Update Channel: release User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0 Multiprocess Windows: 0/3 (default: false) Crash Reports for the Last 3 Days --------------------------------- Report ID: bp-b68a490e-6881-4788-bc36-d14092150716 Submitted: 37 minutes ago Report ID: bp-980c4528-9bec-4a3e-bf00-3c4be2150714 Submitted: 2 days ago All Crash Reports Extensions ---------- Name: Adblock Plus Version: 2.6.9.1-signed Enabled: true ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d} Name: Dangerous Websites Blocker Version: 4.5.3.8 Enabled: true ID: content_blocker_6418E0D362104DADA084DC312DFA8ABC@kaspersky.com Name: Download Panel Tweaker Version: 0.2.4.1-signed Enabled: true ID: downloadPanelTweaker@infocatcher Name: DownThemAll! Version: 2.0.18.1-signed Enabled: true ID: {DDC359D1-844A-42a7-9AA1-88A850A938A8} Name: eCleaner Version: 1.4.1-signed Enabled: true ID: {c72c0c73-4eb0-4fb3-af0f-074e97326cfd} Name: Enhanced Steam Version: 7.2.2 Enabled: true ID: jid0-SmvlvxGpvCyG252KbVMqIKR79Uc@jetpack Name: Firebug Version: 2.0.11 Enabled: true ID: firebug@software.joehewitt.com Name: Flagfox Version: 5.1.0 Enabled: true ID: {1018e4d6-728f-4b20-ad56-37578a4de76b} Name: Greasemonkey Version: 3.2 Enabled: true ID: {e4a8a97b-f2ed-450b-b12d-ee082ba24781} Name: MAFIAAFire Redirector Version: 0.9d.1-signed Enabled: true ID: MafiaaFire@mafiaafire.com Name: MAFIAAFIRE: Gee! No evil! Version: 1.0.0.0.1-signed Enabled: true ID: CustomGoogle@mafiaafire.com Name: Pushbullet Version: 179.1-signed Enabled: true ID: jid1-BYcQOfYfmBMd9A@jetpack Name: RoboForm Toolbar for Firefox Version: 7.9.14.4 Enabled: true ID: {22119944-ED35-4ab1-910B-E619EA06A115} Name: Safe Money Version: 4.5.3.8 Enabled: true ID: online_banking_69A4E213815F42BD863D889007201D82@kaspersky.com Name: SoundCloud Downloader - Technowise Version: 0.94.1-signed Enabled: true ID: {c8d3bc80-0810-4d21-a2c2-be5f2b2832ac} Name: Speed Dial Version: 0.9.6.17.1-signed Enabled: true ID: {64161300-e22b-11db-8314-0800200c9a66} Name: Virtual Keyboard Version: 4.5.3.8 Enabled: true ID: virtual_keyboard_294FF26A1D5B455495946778FDE7CEDB@kaspersky.com Name: Adobe Acrobat - Create PDF Version: 1.2 Enabled: false ID: web2pdfextension@web2pdf.adobedotcom Name: Adobe Contribute Toolbar Version: 6.1 Enabled: false ID: {01A8CA0A-4C96-465b-A49B-65C46FAD54F9} Name: Page Speed Version: 1.12.9.2 Enabled: false ID: {e3f6c2cc-d8db-498c-af6c-499fb211db97} Name: ReloadEvery Version: 28.0.2.1-signed Enabled: false ID: {888d99e7-e8b5-46a3-851e-1ec45da1e644} Name: Stylish Version: 2.0.2.1-signed Enabled: false ID: {46551EC9-40F0-4e47-8E18-8E5CF550CFB8} Name: WordWeb one-click lookup Version: 5.0.4406 Enabled: false ID: wcapturex@deskperience.com Graphics -------- Adapter Description: NVIDIA GeForce GTX 780 Adapter Drivers: nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Adapter RAM: 3072 Asynchronous Pan/Zoom: none Device ID: 0x1004 Direct2D Enabled: true DirectWrite Enabled: true (6.2.9200.17292) Driver Date: 4-8-2015 Driver Version: 9.18.13.5012 GPU #2 Active: false GPU Accelerated Windows: 3/3 Direct3D 11 (OMTC) Subsys ID: 36041458 Vendor ID: 0x10de WebGL Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GTX 780 Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d 1.1 AzureContentBackend: direct2d 1.1 AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0 Important Modified Preferences ------------------------------ accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 358400 browser.cache.disk.filesystem_reported: 1 browser.cache.disk.smart_size_cached_value: 358400 browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.frecency_experiment: 4 browser.download.importedFromSqlite: true browser.download.manager.alertOnEXEOpen: true browser.download.useDownloadDir: false browser.places.smartBookmarksVersion: 7 browser.search.useDBForOrder: true browser.sessionstore.enabled: true browser.sessionstore.upgradeBackup.latestBuildID: 20150630154324 browser.startup.homepage: chrome://speeddial/content/speeddial.xul browser.startup.homepage_override.buildID: 20150630154324 browser.startup.homepage_override.mstone: 39.0 browser.tabs.closeWindowWithLastTab: false browser.tabs.warnOnOpen: false browser.urlbar.default.behavior: 0 browser.urlbar.maxRichResults: 15 dom.allow_scripts_to_close_windows: true dom.mozApps.used: true extensions.lastAppVersion: 39.0 font.internaluseonly.changed: true gfx.direct3d.last_used_feature_level_idx: 0 media.gmp-eme-adobe.lastUpdate: 1434346322 media.gmp-eme-adobe.version: 11 media.gmp-gmpopenh264.lastUpdate: 1431777838 media.gmp-gmpopenh264.version: 1.4 media.gmp-manager.buildID: 20150630154324 media.gmp-manager.lastCheck: 1436965035 media.peerconnection.enabled: false network.cookie.prefsMigrated: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1436856493 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true plugin.state.anti_banner_native_proxy: 2 plugin.state.npcontentblocker: 2 plugin.state.nponlinebanking: 2 plugin.state.npvkplugin: 2 plugin.state.url_advisor: 2 print.printer_\\server\Brother_HL-2040_series.print_bgcolor: false print.printer_\\SERVER\Brother_HL-2040_series.print_bgcolor: false print.printer_\\server\Brother_HL-2040_series.print_bgimages: false print.printer_\\SERVER\Brother_HL-2040_series.print_bgimages: false print.printer_\\server\Brother_HL-2040_series.print_colorspace: print.printer_\\SERVER\Brother_HL-2040_series.print_colorspace: print.printer_\\server\Brother_HL-2040_series.print_command: print.printer_\\SERVER\Brother_HL-2040_series.print_command: print.printer_\\server\Brother_HL-2040_series.print_downloadfonts: false print.printer_\\SERVER\Brother_HL-2040_series.print_downloadfonts: false print.printer_\\server\Brother_HL-2040_series.print_duplex: -14379768 print.printer_\\SERVER\Brother_HL-2040_series.print_duplex: 1515870810 print.printer_\\server\Brother_HL-2040_series.print_edge_bottom: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_edge_bottom: 0 print.printer_\\server\Brother_HL-2040_series.print_edge_left: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_edge_left: 0 print.printer_\\server\Brother_HL-2040_series.print_edge_right: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_edge_right: 0 print.printer_\\server\Brother_HL-2040_series.print_edge_top: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_edge_top: 0 print.printer_\\server\Brother_HL-2040_series.print_evenpages: true print.printer_\\SERVER\Brother_HL-2040_series.print_evenpages: true print.printer_\\server\Brother_HL-2040_series.print_footercenter: print.printer_\\SERVER\Brother_HL-2040_series.print_footercenter: print.printer_\\server\Brother_HL-2040_series.print_footerleft: &PT print.printer_\\SERVER\Brother_HL-2040_series.print_footerleft: &PT print.printer_\\server\Brother_HL-2040_series.print_footerright: &D print.printer_\\SERVER\Brother_HL-2040_series.print_footerright: &D print.printer_\\server\Brother_HL-2040_series.print_headercenter: print.printer_\\SERVER\Brother_HL-2040_series.print_headercenter: print.printer_\\server\Brother_HL-2040_series.print_headerleft: &T print.printer_\\SERVER\Brother_HL-2040_series.print_headerleft: &T print.printer_\\server\Brother_HL-2040_series.print_headerright: &U print.printer_\\SERVER\Brother_HL-2040_series.print_headerright: &U print.printer_\\server\Brother_HL-2040_series.print_in_color: true print.printer_\\SERVER\Brother_HL-2040_series.print_in_color: true print.printer_\\server\Brother_HL-2040_series.print_margin_bottom: 0.5 print.printer_\\SERVER\Brother_HL-2040_series.print_margin_bottom: 0.5 print.printer_\\server\Brother_HL-2040_series.print_margin_left: 0.5 print.printer_\\SERVER\Brother_HL-2040_series.print_margin_left: 0.5 print.printer_\\server\Brother_HL-2040_series.print_margin_right: 0.5 print.printer_\\SERVER\Brother_HL-2040_series.print_margin_right: 0.5 print.printer_\\server\Brother_HL-2040_series.print_margin_top: 0.5 print.printer_\\SERVER\Brother_HL-2040_series.print_margin_top: 0.5 print.printer_\\server\Brother_HL-2040_series.print_oddpages: true print.printer_\\SERVER\Brother_HL-2040_series.print_oddpages: true print.printer_\\server\Brother_HL-2040_series.print_orientation: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_orientation: 0 print.printer_\\server\Brother_HL-2040_series.print_page_delay: 50 print.printer_\\SERVER\Brother_HL-2040_series.print_page_delay: 50 print.printer_\\server\Brother_HL-2040_series.print_paper_data: 9 print.printer_\\SERVER\Brother_HL-2040_series.print_paper_data: 9 print.printer_\\server\Brother_HL-2040_series.print_paper_height: 11.00 print.printer_\\SERVER\Brother_HL-2040_series.print_paper_height: 11.00 print.printer_\\server\Brother_HL-2040_series.print_paper_name: print.printer_\\SERVER\Brother_HL-2040_series.print_paper_name: print.printer_\\server\Brother_HL-2040_series.print_paper_size_type: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_paper_size_type: 0 print.printer_\\server\Brother_HL-2040_series.print_paper_size_unit: 1 print.printer_\\SERVER\Brother_HL-2040_series.print_paper_size_unit: 1 print.printer_\\server\Brother_HL-2040_series.print_paper_width: 8.50 print.printer_\\SERVER\Brother_HL-2040_series.print_paper_width: 8.50 print.printer_\\server\Brother_HL-2040_series.print_plex_name: print.printer_\\SERVER\Brother_HL-2040_series.print_plex_name: print.printer_\\server\Brother_HL-2040_series.print_resolution: -489271936 print.printer_\\SERVER\Brother_HL-2040_series.print_resolution: 1515870810 print.printer_\\server\Brother_HL-2040_series.print_resolution_name: print.printer_\\SERVER\Brother_HL-2040_series.print_resolution_name: print.printer_\\server\Brother_HL-2040_series.print_reversed: false print.printer_\\SERVER\Brother_HL-2040_series.print_reversed: false print.printer_\\server\Brother_HL-2040_series.print_scaling: 1.00 print.printer_\\SERVER\Brother_HL-2040_series.print_scaling: 1.00 print.printer_\\server\Brother_HL-2040_series.print_shrink_to_fit: true print.printer_\\SERVER\Brother_HL-2040_series.print_shrink_to_fit: true print.printer_\\server\Brother_HL-2040_series.print_to_file: false print.printer_\\SERVER\Brother_HL-2040_series.print_to_file: false print.printer_\\server\Brother_HL-2040_series.print_unwriteable_margin_bottom: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_unwriteable_margin_bottom: 0 print.printer_\\server\Brother_HL-2040_series.print_unwriteable_margin_left: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_unwriteable_margin_left: 0 print.printer_\\server\Brother_HL-2040_series.print_unwriteable_margin_right: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_unwriteable_margin_right: 0 print.printer_\\server\Brother_HL-2040_series.print_unwriteable_margin_top: 0 print.printer_\\SERVER\Brother_HL-2040_series.print_unwriteable_margin_top: 0 print.printer_Brother_MFC-990CW_Printer.print_bgcolor: false print.printer_Brother_MFC-990CW_Printer.print_bgimages: false print.printer_Brother_MFC-990CW_Printer.print_colorspace: print.printer_Brother_MFC-990CW_Printer.print_command: print.printer_Brother_MFC-990CW_Printer.print_downloadfonts: false print.printer_Brother_MFC-990CW_Printer.print_duplex: -14379768 print.printer_Brother_MFC-990CW_Printer.print_edge_bottom: 0 print.printer_Brother_MFC-990CW_Printer.print_edge_left: 0 print.printer_Brother_MFC-990CW_Printer.print_edge_right: 0 print.printer_Brother_MFC-990CW_Printer.print_edge_top: 0 print.printer_Brother_MFC-990CW_Printer.print_evenpages: true print.printer_Brother_MFC-990CW_Printer.print_footercenter: print.printer_Brother_MFC-990CW_Printer.print_footerleft: &PT print.printer_Brother_MFC-990CW_Printer.print_footerright: &D print.printer_Brother_MFC-990CW_Printer.print_headercenter: print.printer_Brother_MFC-990CW_Printer.print_headerleft: &T print.printer_Brother_MFC-990CW_Printer.print_headerright: &U print.printer_Brother_MFC-990CW_Printer.print_in_color: true print.printer_Brother_MFC-990CW_Printer.print_margin_bottom: 0.5 print.printer_Brother_MFC-990CW_Printer.print_margin_left: 0.5 print.printer_Brother_MFC-990CW_Printer.print_margin_right: 0.5 print.printer_Brother_MFC-990CW_Printer.print_margin_top: 0.5 print.printer_Brother_MFC-990CW_Printer.print_oddpages: true print.printer_Brother_MFC-990CW_Printer.print_orientation: 1 print.printer_Brother_MFC-990CW_Printer.print_page_delay: 50 print.printer_Brother_MFC-990CW_Printer.print_paper_data: 9 print.printer_Brother_MFC-990CW_Printer.print_paper_height: 11.00 print.printer_Brother_MFC-990CW_Printer.print_paper_name: print.printer_Brother_MFC-990CW_Printer.print_paper_size_type: 0 print.printer_Brother_MFC-990CW_Printer.print_paper_size_unit: 1 print.printer_Brother_MFC-990CW_Printer.print_paper_width: 8.50 print.printer_Brother_MFC-990CW_Printer.print_plex_name: print.printer_Brother_MFC-990CW_Printer.print_resolution: -489271936 print.printer_Brother_MFC-990CW_Printer.print_resolution_name: print.printer_Brother_MFC-990CW_Printer.print_reversed: false print.printer_Brother_MFC-990CW_Printer.print_scaling: 1.00 print.printer_Brother_MFC-990CW_Printer.print_shrink_to_fit: true print.printer_Brother_MFC-990CW_Printer.print_to_file: false print.printer_Brother_MFC-990CW_Printer.print_unwriteable_margin_bottom: 0 print.printer_Brother_MFC-990CW_Printer.print_unwriteable_margin_left: 0 print.printer_Brother_MFC-990CW_Printer.print_unwriteable_margin_right: 0 print.printer_Brother_MFC-990CW_Printer.print_unwriteable_margin_top: 0 privacy.cpd.downloads: false privacy.cpd.formdata: false privacy.cpd.history: false privacy.cpd.sessions: false privacy.donottrackheader.enabled: true privacy.donottrackheader.value: 1 privacy.sanitize.migrateFx3Prefs: true privacy.sanitize.timeSpan: 0 security.disable_button.openCertManager: false storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1436856491 user.js Preferences ------------------- Your profile folder contains a user.js file, which includes preferences that were not created by Firefox. Important Locked Preferences ---------------------------- JavaScript ---------- Incremental GC: true Accessibility ------------- Activated: false Prevent Accessibility: 0 Library Versions ---------------- NSPR Expected minimum version: 4.10.8 Version in use: 4.10.8 NSS Expected minimum version: 3.19.2 Basic ECC Version in use: 3.19.2 Basic ECC NSSSMIME Expected minimum version: 3.19.2 Basic ECC Version in use: 3.19.2 Basic ECC NSSSSL Expected minimum version: 3.19.2 Basic ECC Version in use: 3.19.2 Basic ECC NSSUTIL Expected minimum version: 3.19.2 Version in use: 3.19.2 Experimental Features ---------------------

Updated to Windows 10, problem still existed. Then did a clean reinstall of Windows 10, problem still exists.

Since Google updated the html5 player (look different, sorry can't find where it says what version on the html5 player google is using now) I have not had the audio out of sync after 7 to 10 minutes. Yippee!!!!! I'm using Firefox 39.0

Anthony, this A/V sync issue is still affecting some people on YouTube HTML5 video. Do you know of any related bugs?

New YouTube HTML5 player mentioned by comment #15 didn't change anything for me. Still out of sync after 7 or 8 minutes and continuously getting more out of sync.

Same here even with new youtube player, currently on Windows 10, Waterfox 39. Same behavior. The only version it worked perfectly in was v37. Must be some internal issue with DASH (since there's separate streams for video and audio).

Same issue. about:support at http://cryptb.in/pnULv

Still not working with Firefox 40.0 Is there even still info required or is someone working on this? It's broken for me since 3 months now, which would be fine if I weren't on the release channel plus YouTube not offering any option to go back to using Flash.

Bug 1192679 is a similar A/V sync issue.

Can you try Beta 41 ?

Just tried Firefox 41 Beta 1, still same problem, still on the 6-7 minute mark happening. Also used a new and clean profile.

cpearce thinks this A/V sync problem might also lead to EME crash bug 1173632.

Deepil, can you try with 42 or Nightly ?

Firefox 42.0a2: same problem. Firefox 43.0a1: same problem. All releases after Firefox 37 are not working and suffer the exact same bug.

Could you do a right click on the playback window and select stats for nerd and copy the output of it? Thank you

This is from a random video long enough and right after it started to get out of sync, at about the 7min mark. Video ID: fRMxZ59TUcI Dimensions: 1920 x 1080 Resolution: 1920 x 1080@25 Volume: 100% Stream Host: r15---sn-4g57kn7d Stream Type: https CPN: M8KG9E0vog5vu2dc Mime Type: video/mp4; codecs="avc1.640028" DASH: yes (137/140) Connection Speed: 68942 Kbps Dropped Frames: 2/10464

I think it needs to be pointed out that this bug doesn't "wait" until "several minutes in" to happen as some posters here are saying. It happens pretty much immediately. It's just so slight at first that you wont notice it right away unless you're watching footage of something very timing dependent. Something that would fit the bill of timing dependent that makes it obvious pretty much immediately, and what i personally used to test this every time post-37, is footage of a music/rhythm game. Nothing makes it stand out right away better than that.

There were several related A/V sync bugs. One caused a fixed offset between the audio and video (typically 100ms) which is within the range that some people would notice and others not. Others caused a gradual drift of A/V sync. They should all be fixed by the patches in bug 1136360 and we should probably mark this bug as a duplicate of bug 1136360 (although I don't understand the link between this bug and bug 1173632). Test builds should be available in http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/mgregan@mozilla.com-95b50562dd3b/ in a few hours for anyone keen to try them.

Just tried your test build. It's working! Video stayed perfectly sync over at least 15 minutes! Any chance that this will make it to Firefox 41 before release?

(In reply to DeepII from comment #31) > Just tried your test build. It's working! Video stayed perfectly sync over > at least 15 minutes! Any chance that this will make it to Firefox 41 before > release? Thanks for testing and reporting back!