User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:37.0) Gecko/20100101 Firefox/37.0 Build ID: 20150415140819 Steps to reproduce: Go to YouTube (just example for video) with hardware acceleration enabled: videos are low contrast, less vibrant, bleached. Go to YouTube with hardware acceleration disabled and videos are as they should be with normal contrast, vibrant colors and so on. See screenshots. Actual results: Videos are low contrast, less vibrant, bleached. Expected results: Videos are normal contrast, vibrant colors and so on.

Forgot to mention: this has been going on some time now. I use NVidia Geforce drivers and they are always up to date. Using GeForce 350.12 now. At the Mozilla forum it was suggested that there could be issues with graphics driver and Firefox.

Type about:support in the location bar and paste here the section "graphics".

This is with Hardware acceleration enabled and giving the bad video play: Adapter-RAM 4095 Adapterbeschrijving NVIDIA GeForce GTX 970 Adapterstuurprogramma’s nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um ClearType-parameters Gamma: 2200 Pixel Structure: R ClearType Level: 50 Enhanced Contrast: 100 Datum stuurprogramma 4-8-2015 Device-ID 0x13c2 Direct2D ingeschakeld true DirectWrite ingeschakeld true (6.3.9600.17415) GPU #2 actief false GPU-versnelde vensters 1/1 Direct3D 11 (OMTC) Stuurprogrammaversie 9.18.13.5012 Subsys-ID 31601462 Vendor-ID 0x10de WebGL-renderer Google Inc. -- ANGLE (NVIDIA GeForce GTX 970 Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote true AzureCanvasBackend direct2d 1.1 AzureContentBackend direct2d 1.1 AzureFallbackCanvasBackend cairo AzureSkiaAccelerated 0

This is with Hardware acceleration disabled and giving the good video play: Adapter-RAM 4095 Adapterbeschrijving NVIDIA GeForce GTX 970 Adapterstuurprogramma’s nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um ClearType-parameters Gamma: 2200 Pixel Structure: R ClearType Level: 50 Enhanced Contrast: 100 Datum stuurprogramma 4-8-2015 Device-ID 0x13c2 DirectWrite ingeschakeld false (6.3.9600.17415) GPU #2 actief false GPU-versnelde vensters 0/1 Basic (OMTC) Stuurprogrammaversie 9.18.13.5012 Subsys-ID 31601462 Vendor-ID 0x10de WebGL-renderer Google Inc. -- ANGLE (NVIDIA GeForce GTX 970 Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote true AzureCanvasBackend skia AzureContentBackend cairo AzureFallbackCanvasBackend cairo AzureSkiaAccelerated 0

Extra info: in the NVidia Control Panel it is set that programs decide what settings to use. So I made no changes to those settings, these are default NVidia settings. And I leave it that way because changes in that section are system wide.

Some more info: I tried it with webgl.disabled in about:config and hardware acceleration enabled but video is still not good. So WebGL is not the cause.

It looks like the hardware-accel version's black isn't true black. Decoding issue? Compositing?

Marking as a duplicate of bug 1161349 since that bug has some existing investigation in it.