Since mp4 is a more common video format you may concider converting files to mp4, I suggest searching web because there is number of free methods that can for this for you.
Sounds like the audio may be in a unsupported format, try Rock Player from https://market.android.com/details?id=com.redirectin.rockplayer.android.unified.lite&feature=search_result it supports more formats than stock player..
If this doesn't work then you may have to encode in a supported format.
Gave it a try, didn't work for me. All you could hear was really loud static. Thanks though for the suggestion.
Thanks, that worked. Used a free program from www.dvdvideosoft.com. Simple to use worked beautifully.
