Apple refuse to implement Ogg and went with H.264. Opera refuse to use H.264 because of the licensing costs. Google use H.264 and Ogg but can't redistribute H.264 in an open source way and say Ogg just isn't ready for sites like YouTube. Mozilla refuses
H.264 because of patent problems.
So you have two browsers not supporting the prefered format for the web's main video site YouTube. And there's no way to nominate a codec in the spec. So how exactly is this going to work?
(And again users don't care what format their video is in as long as it gets shown. And Flash supported H.264 in Flash 9 in December 2007. Flash works right now. Users see the piano playing kitten. That's all they care about)