Real Player is now in the Medibuntu repository. To activate it, copy and paste this code in the terminal:

sudo wget --output-document=/etc/apt/sources.list.d/medibuntu.list http://www.medibuntu.org/sources.list.d/$(lsb_release -cs).list && sudo apt-get --quiet update && sudo apt-get --yes --quiet --allow-unauthenticated install medibuntu-keyring && sudo apt-get --quiet update

Then, run this code:

sudo apt-get install realplayer