Yeah but what are the chances of including the VP8 codec in a default IE9 installation? (Safari will be able to use VP8 as a QuickTime plugin, too. The million-dollar question is whether the codec will be available out of the box.)
A valid WebM file can only contain VP8 video and Vorbis audio in a .webm container. Why did you define WebM so narrowly?
We decided to define WebM files in this way because we wanted to do whatís best for users. Users just want video to work, they donít want to worry about supported codecs, file formats, and so on. After much discussion with browser makers, tool developers and others, we reached a consensus that a narrowly defined format would cause the least confusion for users. If a user has a .webm file, they can be confident that it will play in any browser or media player that supports WebM.
Edit: this is a reply to yotambien's previous post on patent revocation. Ninja'd!
This "revocation" clause is standard fare for all patent-holders. Check Microsoft's "community promise", for instance. This is the basis for all defensive patents: "feel free to use our patent portfolio but sue us and we'll make sure you will regret this later".
While this mechanism works well for entities that sell actual products/services (e.g. IBM vs Microsoft vs Apple), it doesn't work at all for parasites that have no product. That's why patent trolls are so dangerous and that's why almost everyone is asking for patent reform.
IE9 will support playback of H.264 video as well as VP8 video when the user has installed a VP8 codec on Windows.
A very smart move indeed. A subset of Matroska guaranteeing good streaming, and playback support; ready patches for every meaningful software out there. Youtube transcoded, and just about everyone pitching in to say they support it.
What's Apple's stance? They're the one player so far missing.