I haven't been able to get southpark.cc.com to play any episodes. It may be because they want me to sign in first. I'm not sure. However, I have found a better alternative. This may be old news but I only just discovered it so am passing it on in case it helps anyone else.

The Dutch Southpark site has all episodes, in English, and they play without any problem as long as you have the right dns proxy. With Unotelly just set Channel Option 5 to The Netherlands and go to http://www.southpark.nl/full-episodes.