If you have received this error, you will need to install an additional codec, filter, or software to decode the audio track of your video file.
First, make sure you know the format of the audio track in your file. If you aren't sure, you can open the file in a program like Media Info
and look under the Audio Stream section to find this out. You can also open a video in DivX Player Player, you can right-click on the playback screen and select "Show Video Information".
Once you know the format of your audio track, check this list of Additional Filters here
for more information and links to download the appropriate filters, for both Windows and Mac.