I've found it to be pretty bad in the video streaming stakes, but apps like Kontorri's UK tube and Afleggs conversion website have made it possible to view selected flash video sites. (youtube and dailymotion so far...)

video playback requires a program called media converter which makes a video file compatible with the 770, it's free and you can find it by searching these forums. It's a bit of hassle, but with some jiggery pokery it's possible to do a lot of stuff with the 770.