Not sure if this has already been figured out, or maybe it is useless so no one cares, but i figured i would share it anyway...
I still had one of these old Universal Docks with the S-Video Out on it, and decided to see if it would work with my 3G Iphone...
i plugged it in and it said this accessory is not meant for the iphone blah blah blah
i proceeded to play a video and it poped a box and said display on TV? i clicked yes, and voila... i had video going out via the S-Video connector on the back of my Dock.
-enjoy