What type of hardware/equipment are you using?
what are you trying to play/stream/burn avi, mpeg 1234, real, wmv, ogg?
what programs/apps are you attempting to use?
Have you installed the 3rd party and backport repos, such that you have all needed codecs available? have you installed them as well?
do you even have the foggiest idea what i'm asking?
we need your knowledge level, your system, and your equipment, and possibly the isp you're using in this instance to get an idea of your situation and how to help.