Youtube has been Hd for a few weeks now,
but this morning (I believe) Youtube
gave me a christmas gift: A bigger window when my video are played in HD.

First its normal size, but when you prees HD the player grow much bigger.
Sorry I don't have the pixel measurement.
Only bad point is that when video is not HD or High quality it more ugly
than it was beforethe HD switch.

try this

YouTube - Pascale Picard&Paul McCartney in HD (http://www.youtube.com/watch?v=yao1Aij2lhM&feature=channel_page)

yeah. Looks like its the same HD files from before but now its in a bigger screen. From the videos I have seen I think the videos looked better before the larger window. Still looks the same when full screen.

I just uploaded my first HD video to YouTube today and I was amazed at how great the quality is now, and especially the audio. YouTube has improved so much over the last few months. Now they just need to have a premium account that avoids advertisements and it will be perfect.

Big window is nice but the video look very ugly before you press on HD, I think a lot of users do not press HD.
Maybe the advertisement is what keeping youtube free.