I wouldn’t believe it if I hadn’t seen it myself. This is a typical-quality youtube video:

This is an ultra-high quality Youtube video:

Notice the completely inaccurate timecode for the section (and it’s just a hair below the 10 minute YouTube limit). The sound and video quality are just awesome - pop it up to full screen and it just looks great.

It’s not easy on the bandwidth; but it really shows you what even a basic flash player like Youtube’s is capable of. I think Flash video is the future of web-distributed video and audio.