In a recent message that has come as a shock to many, Microsoft endorsed the use of <video> and <audio> tags. Adrian Bateman, the Program Manager for Internet Explorer, posted about this a few weeks ago.
The new HTML5 specification includes these <video> and <audio> tags to allow for both video and audio to be played from the browser without the use of a plugin, like Flash or QuickTime. This allows for open, royalty-free codecs like Ogg Theora to be widely utilized. It also frees video and audio from its current, largely proprietary grasp, which reduces the legal and technological costs of entry, allowing for more participatory media. Many new browsers support these HTML5 elements, such as Firefox 3.5, Safari 4, Chrome, and Opera 10. Internet Explorer, which holds the largest market share for browsers, was conspicuously missing from this list. By announcing its support, IE has potentially allowed for a much larger base upon which this new HTML5 framework can be built—though what will actually happen remains to be seen.
Source: Open Video Alliance