I opted into the beta You Tube HTML5 player option, and it gives a little summary of the browser support for video formats out there now:
Supported Browsers We support browsers that support both the video tag in HTML5 and either the h.264 video codec or the WebM <http://webmproject.org/> format (with VP8 codec). These include: - Firefox 4 (WebM, Beta available here<http://www.mozilla.com/en-US/firefox/beta/> ) - Google Chrome (WebM and h.264) - Opera 10.6+ (WebM, Available here<http://www.opera.com/browser/download/> ) - Apple Safari (h.264, version 4+) - Microsoft Internet Explorer 9 (h.264, Beta available here<http://ie.microsoft.com/testdrive/> ) - Microsoft Internet Explorer 6, 7, or 8 with Google Chrome Frame installed (Get Google Chrome Frame<http://code.google.com/chrome/chromeframe/> )
