RealPlayer is a closed source cross-platform media player by RealNetworks that plays a number of multimedia formats including MP3, MPEG-4, QuickTime, Windows Media, and multiple versions of proprietary RealAudio and RealVideo formats.
Note: The .deb package currently available from the RealNetworks site is a 32-bit build of RealPlayer. The .deb file available from the Medibuntu repository will run on 64-bit systems.
Installing RealPlayer:
Add the Medibuntu Repositories, RealPlayer is available through the Medibuntu non-free repository.
The following command will register the Medibuntu repository with your system's Advanced Packaging Tool (APT) and import the Medibuntu keyring. The command should be run in the Terminal (Applications -> Accessories -> Terminal). The command is not release specific - it will determine which version of Ubuntu is running and install the appropriate repositories.
sudo wget http://www.medibuntu.org/sources.list.d/`lsb_release -cs`.list --output-document=/etc/apt/sources.list.d/medibuntu.list
sudo apt-get -q update
sudo apt-get --yes -q --allow-unauthenticated install medibuntu-keyring
sudo apt-get -q update
A line similar to the following will be created in /etc/apt/sources.list.d/medibuntu.list. The entry will reflect the codename of the Ubuntu release you are currently using.
Open the Terminal via Applications > Accessories > Terminal.
sudo apt-get update
sudo apt-get install realplayer
The default installation location is /opt/real/RealPlayer.
source:http://linuxpoison.blogspot.com/2010/09/13578167759539.html