Prepping my gear for CES today, I dropped a few movies from my Mac onto my BlackBerry PlayBook. Since I've made the mistake in the past, I decided to test them out before hitting the road. Sure enough, two of the videos I had imported had no sound -- thus I embarked on my quest to the CrackBerry forums for an easy solution. If you're having problems with no sound on your PlayBook videos, keep reading and we'll get you squared away in no time!
So off the bat we're assuming the videos with which you're sound having issues are .avi files. The PlayBook only supports certain file types, so any .avi videos with AC3 audio won't play. To fix the issue you'll have to convert the audio to MP3.
When Avidemux is done processing (it should only be a few minutes depending on your PC setup), toss the video on your PlayBook and you should have glorious audio!!