>>5
Strange that you mention 3.6, as that is one of the very last good versions of FireFox. I agree, HTML5 only adds additional complexity with little substance.
>>6
It's definitely enough for the applications that GIF is used for. It's not meant to be a replacement for video.
>>7
Flash was good when it was still Macromedia and not Adobe. The video tag is nice but the stupid codec wars are not. Whatever happened to "use whatever codecs the user has installed"?
I'm willing to bet 90% of video-viewing users already have Xvid (MPEG-4) or H.264 or some similar codec on their system, so why not use that. ffdshow is a good FOSS implementation. Eliminates all the licensing/patent issues, because then Mozilla/Google/whoever don't need to ship codecs with their browsers.