From LQWiki

This guide is meant to be a way to generically install Linux codecs on virtually any distribution.

Codecs cannot come pre-installed on most Linux distributions because of patent and/or copyright issues.

Installing these codecs should allow you to play most video and audio files you can find on the internet. (avi, mp3, mov, etc.)

Quick Steps

1. Install mplayer as described on the page mplayer.

Now you should be able to watch any movie under Linux using gmplayer.

See also

• http://news.softpedia.com/news/How-to-Install-Multimedia-Codecs-in-Linux-39555.shtml
• Howto install win32 codecs on x86_64 architecture