I went searching and found out that this is an on going issue with Nvidia graphics cards lately. A suggestion was made to try older drivers instead of the newer ones and on some it worked on others it didn't

NVIDIA Forums -> GeForce 8600 gt and S video

Someone thought it was because of the Svideo cable to RCA plug that might be causeing the problem... What you might try is to convert the Svideo to an adapter instead of using a converted cable.

I will keep searching but no promises!