"Even without HTML 5 formally specifying a default video codec, Mozilla's view is that the video tag is still useful.
""The video tag and the video JavaScript API allow developers to treat video as a first-class citizen of the Web," Mozilla Standards Evangelist Arun Ranganathan told InternetNews.com. "There is great value in the Video tag and API, but we are keen to see a common video codec emerge on the Web that is both free to use and of a high quality for Web applications."
"The HTML 5 specification itself is still in the drafting phase, which means the final version could potentially still be adjusted to specifically include a default video codec."