In this most recent build of Firefox Nightly (next stable Firefox 23) includes support for H.264 video hardware acceleration.
This feature will be included in the stable releases for different operating systems.For example, in Firefox 21 (in a few days), hardware support for H.264 is scheduled for release on Windows 7. In the next release of Firefox 22 (a few weeks), hardware support for H.264 will also appear under Windows XP, Mac and Linux.
History with H.264 support is very interesting. This is quite a controversial topic for Mozilla. First, because of the proprietary codec. Second, because of the “betrayal” by Google. This company is still January 11, 2011 has announced that he will refuse to support the H.264 codec in favor of open codec WebM. Soon after, Mozilla and Opera have joined the initiative of Google and also switched to WebM, but the company Google has not made ??a promise to this day.
It so happens that today only Chrome supports both formats, and all other browsers support either WebM, or H.264.