this is easier than you might expect.

fix your sources.list
sudo nano /etc/sources.list
...and add "multiverse" to end of all the lines

update apt
sudo apt-get update

get red5 .deb installer
wget http://www.nielsenaa.com/red5-installers/red5_0.7.0_all.deb

install red5
sudo dpkg -i red5_0.7.0_all.deb

fix any dependency issues
sudo apt-get -f install

check it out @ http://myserver.com:5080 . you should see the red5 page!