I have an 800Mhz Power Mac and I can play Youtube videos up to 480P flawlessly. Your emac should do a better job. Make sure you have the newest version of OWB and read the readme included in the archive on to on how to improve Youtube playback with HTML5. There are a couple of scripts you need to enable. It is pretty easy. Once you enable these scripts, play in overlay mode.

Make sure you spoof as a Youtube supported browser, such as Safari.

[ Edited by redrumloa 10.02.2012 - 10:08 ]