On Jun 13th 2009 Chris DiBona of Google claimed on the WhatWG mailing list:
“If [youtube] were to switch to theora and maintain even a semblance of the current youtube quality it would take up most available bandwidth across the Internet.”
Everyone who has ever encoded a Ogg Theora/Vorbis file and in parallel encoded one with another codec will have to immediately protest. It is sad that even the best people fall for FUD spread by the un-enlightened or the ones who have their own agenda.
Fortunately, Gregory Maxwell from Wikipedia came to the rescue and did an actual “YouTube / Ogg/Theora comparison”. It’s a good read and a comparison on one video. He has put his instructions there, so anyone can repeat it for themselves. You will have to start with a pretty good quality video though to see such differences.