Is there any way to play YouTube Video in <video> tag?

I'm sure there is, but I'm not sure how at this point. Can anyone else reading share some experience with this?

You have to add the html5=1 in the src attribute of the iframe :

<iframe src="http://www.youtube.com/embed/dP15zlyra3c?html5=1"></iframe>

The video will be displayed as HTML5 if available, or fallback into flash player.