main decoder error: no suitable decoder module for fourcc `XVID’

This problem can occur when your Debian Linux system is using packages from main Debian repository as well as from http://www.debian-multimedia.org/ . For example VLC will report a following error:

main decoder error: no suitable decoder module for fourcc `XVI

What needs to be done is to remove vlc and downgrade libavcodec51 package and its dependencies. To do this you can use:

apt-get install --reinstall =0.svn<version>

or remove the package with

dpkg -P 

Once done remove http://www.debian-multimedia.org/ from /etc/apt/sources.list then execute

apt-get update

and install vlc again:

apt-get install vlc