I’m trying to move to Firefox after Chromium lost its sync feature, and it largely works, but I can’t seem to make it play xvid videos.
I don’t have link permissions, but specifically the type listed as MPEG4 at http://demo.nimius.net/video_test.
xvidcore is installed, and if I download the .avi file that can’t be played (http://demo.nimius.net/video_test/videos/test.avi) ffmpeg can decode it just fine. Chromium plays it properly, but Firefox doesn’t.
MP4 / MEPG4 videos were handled by plugins in the past but none are available any more
The long version:
Back when Firefox was still called NetScape, videos were handled by animated GIFs and videos with audio were handled by the QuickTime plug-in from Apple.
A bit later they were handled by Adobe’s Flash player, and nowadays they’re being handled by HTML5, so Mozilla never bothered to include a native MPEG4 video player because MPEG4 has patents associated with their technology and Mozilla is and always has been very much open source.
So now that Adobe’s Flash player has gone the way of the dodois not available any more, no one else bothered to write a new plug-in and Mozilla doesn’t want to touch it with a 10-foot pole.
Having said the above, most modern websites use HTML5 to play videos and only old, crappyunmaintained websites still use MP4, so although there is now a glaring hole in FireFox, it won’t matter much to you. (I haven’t run into any websites like that in years!)
Google, having deep pockets and lots of lawyers, just wrote their own native MP4 decoder (and probably paid the patent fees to the Motion Pictures Group. (.MPGwas the original file extension)