Everyone who said WebM is not free or open should now rethink what open and free means. It's not what it's mostly used, but what's not encumbered by patents or unfair licenses. And WebM is the way to stop the slavery of the Internet while video getting more important.
The FSF wrotes: "We applaud Google for this change; it's a positive step for free software, its users, and everyone who uses the Web. For a while now, watching video on the Web has been fraught with peril. Most of it is delivered with Flash, which is proprietary, nonstandard software. Free software alternatives like GNU Gnash are available, but the user experience isn't always as seamless as it ought to be.
When work began on the next version of the HTML standard, HTML5, work on video delivery and playback was a priority. But while everybody agrees on how the video-tag should look, there's no agreement about how that video should be encoded. Microsoft and Apple support H.264; Mozilla and Opera support WebM and Ogg Theora. For a while, Google has been supporting all of these codecs—but now it's made a bold move to support free standards and drop H.264."
Now that is a clear statement. Read the full post to get more reasons to use WebM in the future.