Here are a few more notes about the new video tag. The video tag is new in html 5 and w3c is still working out the details.

With the new video tag you probably want to be able to control the video from scripts, this is also something w3c is working on and will be part of the new standard. To get an idea of how the api might work you can have a look at the free ogg play Firefox plugin.
The actual html 5 draft also has many details about how the browser should handle media.

The developers of the Opera browser has developed a test version that support the new video tag with a javascript api. Read about the implementation and download a special build.

Quite recently w3c had a workshop about video on the web. There are some interesting interview videos from the conference available

Even with the new video tag in place you need a video capture software to grab preview thumbnails for you web page.