This may or may not be due to the actual video. It may be the poor quality codec/program used to convert it. It might be difficulties divx player has handling some of these files. Sometimes it's handy to try some other players just in case. eg: VLC would be my 1st recommendation. Another is one of the avi players listed here such as the 1st one: CODECs list and alternate players for Movies

Keep in mind that audio for video may be sub-converted using quite a wide range of audio formats. That in itself might be the reason. That's why I recommended trying VLC 1st as it has quite a dynamic range of audio formats. http://www.videolan.org/vlc/features.html