Remember how one of the promises of HTML5 is to allow video to play without having to use flash? Looks like YouTube, who you could say uses Flash video "a lot" is flirting with it. They have an HTML5 Demo page showing off their interface playing a video with no flash involved. Looks good, it's basically YouTube and the only reason you'd know it's not Flash is if you don't have the flash plugin installed or look at the source code.

Once again this is something you'll need a modern browser to see (IE users are left out again :( Hopefully an update sometime soon will include HTML5 in IE).