Thanks to an effort by people at xiph, the creators of the ogg file format and Theora and Vorbis codecs, the HTML5 <video> tag has become a reality in Internet Explorer.
The latest version of the xiph codec pack includes the technical preview of a component which adds support for the HTML5 video element to Internet Explorer. Websites aiming to use this feature need to make a very minimal alteration to their web-page which will enable the usage of this tag.
The caveat, you will not be able to play back videos from websites such as YouTube which use the H.264 codec for the content using the HTML5 video tag (they will still work via Flash though). The only supported format for the <video> tag will be Ogg with Theora video and Vorbis audio. You will be able to play back content from DailyMotion though, which supports this profile, although that too will only work if the required modification have been made at their end.
Since this is just a technical preview, it is intended to merely show that such a thing is possible, and to give a few geek the opportunity to try it before others, than to actually be usable, because right now it isn't. Not much. For now the only supported operation is playing the video, click to play, click to pause. There is no support for seeking in the video, and no support for controls or interfaces. Over time hopefully this will become a a fully featured component for the HTML5 <video> tag in IE.
It is quite sad that the browser which was once responsible for pushing forward new innovative features, now can't even keep up with standards. Is this the same Microsoft which gave the web XMLHttpRequest, the most powerful tool in the Ajax shed? Now 3rd parties have to work to add things such as the canvas tag, the video tag, or go so far as to completely replace the engine.
To enable the feature in IE, you need only to add
xmlns="http://www.w3.org/1999/xhtml/video" to your <video> tag. You can get the codec pack from the xiph website, both 32-bit and 64-bit versions are available.