AV Cable

there are some integrated circuits inside the AV connector, it's not just simple wiring.

Here are the official cables Apple provides for supporting video-out on the various model iPods and iPhones.

You can see in the photos of this article there are indeed chips in the composite AV cable. if you read further down in the comments, there is dispute as to the exact function of these chips, but anyhow these chips exist in the cable.

I've not seen any definitive article proving you can build your own AV cable from scratch with just wiring...