src: http://ubuntuforums.org/showthread.php?t=513901
title: Avidemux2 no sound «Trouble initializing audio device»
@lukeduke
Should be the same as above.
This is how i did it:
Edit>Preferences>Audio
Change Audio Output to ALSA
Under ALSA Device type: default
This also works on my Gutsy Xubuntu.
Changing Audio Output to OSS
and ALSA Device type: default