RealPlayer plugin for Firefox

Totem is the default player for realplayer media files in firefox.
Remove these files in /usr/lib/mozilla-firefox/plugins:
libtotem-complex-plugin.so
libtotem-complex-plugin.xpt

sudo rm /usr/lib/mozilla-firefox/plugins/libtotem-complex-plugin.*

Then install realplayer plugin for firefox:

Add this to /etc/apt/sources.list :
deb http://archive.canonical.com/ubuntu edgy-commercial main

(Do sudo apt-get update)

Then,
sudo apt-get install realplay