Where is the camera in the A320?
There's an option for a tail mounted camera for the passenger entertainment system (PES). It's the same one they use on widebody jets, but it's not hooked up to the cockpit for taxi purposes.

Airbus press release says


  Designed for a private customer, this cabin seats just over 30 passengers and includes such features as touch-screen technology, advanced passenger entertainment and communications, plus a tail-mounted camera.