User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:19.0) Gecko/19.0 Firefox/19.0 Build ID: 20121013044431 Steps to reproduce: Try to play a embedded video on for example facebook or gizmodo (see: http://gizmodo.com/5951663/bats-wolfwrangler) on latest Nightly (19.0a1 2012-10-13) on linux x64. I think it first started happening with the 10-13 build but perhaps a few days before. Actual results: The audio plays normal but the Video stutters, showing only about one frame every five seconds unless you move around your mouse or scroll the page. Reproduced in safemode. The same video works fine on youtube if played there. Expected results: Video plays normally like usual.

Could this be related to the removal of Thebes canvas or does that not come into play here?

I can reproduce the problem Nightly19.0a1 without HWA on Ubuntu12.04 and Windows7. http://hg.mozilla.org/mozilla-central/rev/57304bbf9c0e Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121014030627 Flash player 11.4.402.287 http://hg.mozilla.org/mozilla-central/rev/57304bbf9c0e Mozilla/5.0 (X11; Linux i686; rv:19.0) Gecko/19 Firefox/19.0a1 ID:20121014030627 Flash player 11.2.202.243ubuntu0.12.04.01 Reproduceble: almost always Steps to reproduce: 1. Disable HWA from Tools > Option/Edit > Preferences 2. Open http://gizmodo.com/5951663/bats-wolfwrangler 3. Start Playback 4. Mouse hover toime seekbar to pops up small picture And mouse down and drag(hold mouse down) to horizontal 5. Mouse release and move mouse to empty area of page Actual results: Videwo choppy. but aound seems to be okey. Mouse hover menubar and move left-right continuously then the movie play well. Regression window(m-i) Good: http://hg.mozilla.org/integration/mozilla-inbound/rev/cea04d0eb7c9 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121011155703 Bad: http://hg.mozilla.org/integration/mozilla-inbound/rev/f283941dbf75 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121011163903 Pushlog: http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=cea04d0eb7c9&tochange=f283941dbf75 In local build: Last good : 9f28c28e988f First bad : 0586d2a97c52 Regressed by : 0586d2a97c52 Matt Woodrow — Bug 795674 - Refactor DisplayItemData storage in FrameLayerBuilder. And it seems to be fixed in http://hg.mozilla.org/integration/mozilla-inbound/rev/007e3dea2e57

Embedded videos seem to play fine again with todays build. Fixed?

Fixed by Bug 795674