Hi, I do not know whether it may be the problem or related to this but years ago when I played with easy ubuntu on my n900 I experienced something similar: the system (videos played with mplayer for example) had sound but videos opened with any browser didn't have sound. My solution was to remove pulseaudio completely and installed alsa; then with alsamixergui the youtube videos had sound. Be aware of that when I did this somehow I lost some of my configs (appearence of LXDE for example) so I had to set everything again... jm