I would like to suggest, that if Mozilla implements H.264, Mozilla should also implement free codecs that Safari or Internet Explorer implement. This example of mine only uses a royalty free codec, works in OSX Safari, but does not work in Firefox: http://jjc.freeshell.org/turning_pages.html
It uses Motion JPEG video with uncompressed PCM audio in an AVI container. Admittedly, MJPEG with PCM uses something like a factor of 40 times more bandwidth than H.264, so it is completely impractical for a site like Wikipedia or Youtube (MJPEG is however currently used, for example in Axis Network Cameras). Another possibility (which would need to be verified by lawyers) might be MPEG-1 Video with layer II audio which might be royalty free and is also supported by Safari.
In short, if Mozilla is going to support patent encumbered formats, they should also support royalty free formats that are supported by other browers.