David-
The connectors for video and monitors are called UHF or SO-239 connectors. They were common for baseband video until the late 70's or early 80's when BNC connectors replaced them in the professional video world. The sync and camera connectors probably match specific cameras and equipment made by Sony at the time. With a device like this, all the cameras used must receive a common, external sync signal to avoid jumping or rolling video when switching cameras, or to allow "wipes" and split-screen multi-camera scenes, all of which this device could do. It is only for black-and-white video, not color. Here is a Web site with a few pictures of it:
http://www.labguysworld.com/Sony_SEG-1A.htm