I know there is a button in settings to use the hq videos, but I believe that is only on wifi. I'm pretty sure there is no way to increase the quality over 3G
Even Netflix quality of 3G is terrible. I am in e airport right now (no free wifi) and streaming Netflix video is so awful. I am willing to pay the bandwidth for better quality video.
I'm afraid that it keeps quality down to save on bandwidth, you have to use Wi-Fi to go full quality, even on iPhone the quality of videos is horrible on 3G