This is a myth that MS doesn't support WebM. They do. They just don't ship it in the box. But if you have it on your system, they'll use it. MS doesn't ship a lot of its own technologies in the box -- it doesn't mean they don't support it.
Microsoft provided an API, and the WebM plugin implements it. That's how this sort of thing is supposed to work. That it doesn't any more (at least, not in the world dominated by a particularly popular mobile device vendor who shall remain nameless lest I be flamed into oblivion) is what I found depressing.
I don’t know i MS opposes WebM or not, but that doesn’t mean they support it: they have an API, you write a codec with that API and it works.
"IE9 supports HTML5 video using WebM for Windows customers who install third-party WebM support."
From (http://blog.webmproject.org/2011/03/introducing-webm-in-inte...) the WebM team says,
"Microsoft collaborated closely with us to make the components fully compatible with HTML5 in IE9, so features such as the <video> tag and its canPlayType method are fully enabled for WebM. Our thanks go out to the Microsoft engineers who provided technical assistance and hosted our team in Redmond last month."
Does this sound like a company that opposes it?
In this context I intend “support” as “endorse”. I don’t think they endorse it, or they would be shipping it with the browser. That doesn’t mean they oppose to it. They implemented an API that allows 3rd party codecs, that’s it.