I've been complaining for a long time that youtube uses such a prehistoric codec as Sorensen, causing IMO vomit inducing image quality.
Apparently they have in fact kept the original versions of the uploaded videos on their servers and are currently converting them to the avc/h264 codec. All you have to do to load the new versions is add &fmt=18 to the end of the url when you open a video. Not all videos work and the quality still isn't anything special, but it is at least acceptable now.
Video links and screenshots:
http://www.youtube.com/watch?v=zAfQwDizpRo&fmt=18
http://youtube.com/watch?v=CQzUsTFqtW0&fmt=18
Apparently they have in fact kept the original versions of the uploaded videos on their servers and are currently converting them to the avc/h264 codec. All you have to do to load the new versions is add &fmt=18 to the end of the url when you open a video. Not all videos work and the quality still isn't anything special, but it is at least acceptable now.
Video links and screenshots:
http://www.youtube.com/watch?v=zAfQwDizpRo&fmt=18
http://youtube.com/watch?v=CQzUsTFqtW0&fmt=18