Step 1: Add the Rpmforge Repo
rpm -Uhv http://apt.sw.be/redhat/el5/en/i386/RPMS.dag/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
Step 2: Add the Macromedia Repo
rpm -Uhv http://linuxdownload.adobe.com/adobe-release/adobe-release-i386-1.0-1.noarch.rpm
Step 3: Install Multimedia Applications
yum -y install libdvdcss libdvdread libdvdplay libdvdnav lsdvd mplayerplug-in mplayer mplayer-gui compat-libstdc++-33 flash-plugin gstreamer-plugins-bad gstreamer-plugins-ugly
Step 4: Installing w32Codecs in order to play everything under the Sun.
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 all popular formats. If you experience any issue or have a better approach feel free to post a reply.
*** UPDATE ***yum install mplayer.i386 mplayer-gui.i386 mplayerplug-in.i386
yum -y install totem-xine vlc xine-lib-extras-nonfree totem-xine-mozplugin