(but not really...)
HTML 5's <video> tag is protocol agnostic—it does not care. You place the protocol in the src attribute as part of the URL. E.g.:
<video src="rtp://myserver.com/path/to/stream">
Your browser does not support the VIDEO tag and/or RTP streams.
</video>
or maybe
<video src="http://myserver.com:1935/path/to/stream/myPlaylist.m3u8">
Your browser does not support the VIDEO tag and/or RTP streams.
</video>
That said, the implementation of the <video> tag is browser specific. Since it is early days for HTML 5, I expect frequently changing support (or lack of support).
From the W3C's HTML5 spec (The video element):
User agents may support any video and audio codecs and container formats