no sound from avi/mp4 files?

One last idea I tried:

I installed a real Ubuntu 12.04, not Lubuntu. Then installed LXDE and made it the default desktop.
Ffmpeg error is gone! However, now I have this error:

AL lib: pulseaudio.c:331 PulseAudio returned minreq :-tlength/2; expect break up

With Unity desktop environment there is no issue and audio in videos is fine in Panda. However, the Unity desktop is too resource hungry for my device to keep running at 30 fps. So if we could figure out how to solve this OpenAL issue, ffmpeg sound would at least work for Ubuntu 12.04 (Panda 1.8.1).