i actually spoke with one of the guys from BlackMagic today at a conference I attended, he explained that they wanted to build a small camera for aerials and used input from multi-rotor enthusiasts that are employees of BlackMagic Design. It was their input that got the composite video output, s-bus, and PWM inputs as well as a few other features added to the camera. Their philosophy is they'll build it and leave it to end users to hack, adapt, integrate, etc. that's also why they used a standard 15 pin format for the connector.
very interesting group of people and just discussing it all with them made me want to pony up the cash to buy one.