Problem is not that Theora isn't capable enough now that MozCo has poured money on it. The problem is that Google and every other video service has already their videos in h264, which is playable in Flash. So if YouTube were to support Theora they'd need to re-encode all their videos, and store them as duplicates.<p>Another problem with Theora is hardware. There is a lot of hardware h264 encoders and decoders, allowing even cellphones to play HD h264. AFAIK there is absolute no Theora hardware currently.