All commands are entered from a terminal window.

Do a sudo apt-get update before you begin

Flash
sudo apt-get install flashplayer-mozilla

RealPlayer
sudo apt-get install realplay

Multimedia Codecs
sudo apt-get install gstreamer0.8-plugins
sudo apt-get install gstreamer0.8-lame
sudo apt-get install gstreamer0.8-ffmpeg
sudo apt-get install w32codecs
sudo apt-get install libdivx4linux
sudo apt-get install lame
sudo apt-get install sox
sudo apt-get install ffmpeg
sudo apt-get install mjpegtools
sudo apt-get install vorbis-tools
gst-register-0.8