Step 1: Add RPMforge repository access for your CentOS system. (Required for the majority of multimedia packages.)
You can read the installation instructions at Installing RPMForge.
Step 2: Install the multimedia applications.
The following steps will use yum to install all the packages needed to have full multimedia support. Note there will be a lot of dependencies.
yum install compat-libstdc++-33 libdvdcss libdvdread libdvdplay libdvdnav lsdvd libquicktime yum install flash-plugin mplayerplug-in mplayer mplayer-gui gstreamer-ffmpeg gstreamer-plugins-bad gstreamer-plugins-ugly
Step 3: Install the w32Codecs. (Required for xvid and other proprietary formats.)
wget www1.mplayerhq.hu/MPlayer/releases/codecs/mplayer-codecs-20061022-1.i386.rpm rpm -ivh mplayer-codecs-20061022-1.i386.rpm wget www1.mplayerhq.hu/MPlayer/releases/codecs/mplayer-codecs-extra-20061022-1.i386.rpm rpm -ivh mplayer-codecs-extra-20061022-1.i386.rpm
You should now have full multimedia and video support for most popular formats.
If you happen to have problems with playing video's (eg. the player crashes or you have no image), try to disable System > Preferences > Desktop Effects (Compiz) and see if that fixes your problems.