HTML5 YouTube viewer: close, but not quite there
The Download Squad team had mixed results watching videos with this viewer. Firefox was a bust - NeoSmart says it's because of proprietary codec issues - but some other browsers worked. I got working video (extremely smooth working video, actually) on both Chrome and Safari for Mac, but no audio. Meanwhile, on the Windows side, fellow Download Squad bloggers report that the HTML5 viewer works well in Chrome 4 in XP, and Chrome 3 on Windows 7.
Meanwhile,YouTube seems to be running its own HTML5 tests, including some examples of new in-browser 3D rendering features. Sounds like this could finally be the end of reliance on Flash ... once your browser supports it, or once YouTube starts supporting OGG Theora, Firefox and Chrome's video format of choice for HTML5.