In its HTML5 support, IE9 will support playback of H.264 video as well as VP8 video when the user has installed a VP8 codec on Windows.
In the post the Author, Dean Hachamovitch, reiterates the company line regarding HTML5: “we’re all in,” but this is not a surprising development at all. H.264 is the de-facto standard for mobile web video. Microsoft doesn’t control H.264, and Apple is the pubic face of the codec. It is in Microsoft’s best interests if H.264 has some (serious) competition. It just so happens that it’s in all of our best interests, too.