Regarding clock, ideally you'd want to be able to genlock them. The goal is to ensure that all input sourced send their video frames at the exact same point in

Regarding clock, ideally you'd want to be able to genlock them. The goal is to ensure that all input sourced send their video frames at the exact same point in time, and that each audio device also samples at the exact same points in time. In the past that was even more important, as you'd want to make sure the scanline of CRTs in the studio and of the camera were perfectly synced.