02-03-2010, 08:31 PM
http://www.apple.com/ipad/features/ wrote:
YouTube
The YouTube app organizes videos so they’re easy to see and navigate. To watch one, just tap it. When you’re watching in landscape, the video automatically plays in full screen. And with its high-resolution display, iPad makes the latest HD YouTube videos look positively amazing.
That doesn't address the "how," but yes, youtube.com knows when MobileSafari accesses it and delivers the other video instead of the Flash version.