Actually, check it out...
If you are connected via WI-FI the video quality is very good and many videos are in stereo, which it seems like no videos are in stereo when i access from a normal pc.
If you are connected via EDGE, the same video is poorer quality and the sound is mono.
I've tried a number of videos and this seems to be the case almost always.
Obviously, it is odd that they went through the trouble of encoding everything twice for high and low speed connection. But, I'm glad they did. This is pretty cutting edge stuff, and I'm sure we are just a couple of years of having the 3g speeds available over most the ATT network, (not to mention an iPhone that will support that), until then this is a nice compromise.
Any way I can get the stereo audio when I watch youtube on my PC? I'm jealous now that the quality of videos can be better on my phone now than on my pc! Ha ha!