No, but browser implementors could implement <video> and define it within the high-level HTML markup language. There is no need for the HTML spec to define elements that can be determined to be necessary by the market. If it provides a framework for creating new elements, the market can come up with the necessary elements. Obviously, every page would not have to define every element in existence before being viewable, there would develop -- organically -- a stock of pre-existing elements in browsers.
You are getting down voted because browser vendors inventing their own tags based on their market research didn't work out so well last time, and the last thing we need is for that to even be suggested again. http://www.webreference.com/dev/html4nsie/prop.html is a list of the kind of crap they came up with. Marquee? Blink! Confusion over Embed and Object, which still exists somewhat to this day.
