Here's the current state of HTML5 video: Microsoft and Apple are betting on H.264, while Firefox, Chrome, and Opera are rooting for WebM. Google was actually in favor of both H.264 and WebM up until earlier this month, when the search giant decided to drop H.264 support completely, even though the former is widely used and the latter is not. The company also announced that it would release WebM plugins for Internet Explorer 9 and Safari. Although IE9 supports H.264, excluding all other codecs, Microsoft is making an exception for WebM, as long as the user installs the corresponding codec, and is helping Google ensure the plug-in works properly.
These plug-in announcements are reminiscent of Adobe's stranglehold on online video with Flash. Certain browsers requiring plug-ins to support WebM video and others requiring plug-ins to support H.264 video is hardly a better solution to what we currently have. All the browser vendors agree that their software should have support for the HTML5 video tag, but they can't seem to agree on a standard that will allow it.
Microsoft's goal is to make sure that if the operating system supports H.264 (Windows 7 does out-of-the-box), then the user can play back said video, regardless of which browser they have installed. Google's goal is to push the world towards WebM. Apple seems to be only interested in H.264, but it has not really joined the conversation yet. Mozilla and Opera refuse to provide support for H.264 because the H.264 patent license agreement isn't cheap. On the other hand, in addition to being new and thus not being widely supported, WebM does not have any hardware decoders like H.264 does. In the mobile world, this is very important because hardware video decoding allows mobile devices to get long battery life and smooth performance for video playback.
"At Microsoft we respect that Windows customers want the best experience of the web including the ability to enjoy the widest range of content available on the Internet in H.264 format," a Microsoft spokesperson said in a statement. "Today, as part of the interoperability bridges work we do on this team, we are making available the Windows Media Player HTML5 Extension for Chrome, which is an extension for Google Chrome to enable Windows 7 customers who use Chrome to continue to play H.264 video. We are committed to ensuring that Windows customers have the best Web experience, and we have been offering for several years now the extremely popular Windows Media Player plug-in for Firefox, which is downloaded by millions of people a month who want to watch Windows Media content."