I know for most of you, this will be nothing new, but for the really new-to-linux users (like me), I thought this might be worth talking about.
I found this location on Canonical to download realplayer:
which had several options for downloading for dapper, edgy and feisty.
I downloaded the deb file to my desktop, and used
right click>>install package
to install the program. This is not the plugin, but the full media player. You will have to accept an end-user license for this install. Basically it says that you can use it for personal use, and not distribute it, yada yada...
During setup, it indicated it was installing something for use with Firefox -not quite sure what - but when I try to play a realplyer file on the web, it pops a box asking to use the external player. Maybe it created a symbolic link? I am sorry I don't know much about this.
You can test the player here: http://guide.real.com/