I have a system that’s affected by either this or #570164. I can verify that back in Karmic fullscreen playback of flash video on this system worked flawlessly. In addition, using the proprietary nvidia driver playback (now in Lucid) works fine, but the nv driver suffers from the stuttering too (the log I’m attaching is from the nv setup). I’d much prefer using the OSS drivers as the proprietary one has its own problems, but currently it’s the only way to go if I want fullscreen flash to work properly.