I don't know what's going on here, but I've heard and read several issues going on with the ipod video output. After coming across this website, and before reading too many reviews/replies, I quickly bought a cheap camcorder a/v cable off eBay. I got it in the other day and it didn't work. I had some bare wires laying around so I just started trying all the options, switching grounds and colors, and every possible combo. After a while, I found something very interesting.
If I used any ground on the a/v cable (any color) as the positive input for the tv and used the positive terminal of that color as the ground for the tv (out of phase), video would work. Next, if I used the red positive as ground, then white positive would output the left audio and yellow positive would output the right audio. However, if I tried to combine video and audio in this fashion, I would get a slight buzz. I'm no electrical expert so if anyone can take this and run with it to figure out whats going on, please do!!!
Again, assume output is with respect to a/v cable, and input is with respect to tv or other device...
ground output = video input
+ red output = ground input
+ white output = left input
+ yellow output = right input
(without video, audio is clear. when mixed, buzz in audio).