Firefox 4, bringing WebM support to the web
This is our first release to include support for WebM. We've been involved with WebM since it was launched and have contributed to its development. It's been in our Mozilla Nightly builds for many months. As part of that, you'll find WebM all over our sites. For example, the Firefox 4 What's New video is in WebM. WebM Video is part of many of our awesome Firefox 4 demos. And if you're part of the Youtube HTML5 beta, a large percentage of the videos you view will be delivered with WebM.
To understand why this is really important you need to understand global market share numbers for browsers. According to StatCounter, Firefox accounts for about 30% market share - or nearly a third of all browser users. When you combine that with Chrome and Opera it means that about 50% of internet users will have access to the high-quality WebM codec over the next few months, following the Firefox 4 adoption curve.
We've supported HTML5 and standards-based video since Firefox 3.5 with Theora and Vorbis support, and we're happy to add WebM to that mix since it offers an even higher-quality option for the web.
--Chris Blizzard, on behalf of Mozilla