I agree Lyle,
Great explanation Paul!. [Linked Image]
This is one area of work that I used to specialise in, with respect to connecting up all sorts of TV (Terrestrial and Satellite) also your now standard DVD and the VCR.
I've been an Aerial Technician for some years now and even after the Sky fella has run-away, I still get sent to places where the system is quite simple, but if you've ever seen the standard jumble of cables behind the Main TV, it can be quite daunting.
The system that Paul explained is pretty much universal as far as reticulation goes.
There are systems around, with a Remote Extender, where you have all of the equipment in one place, apart from the TV's (of course) and you point your remote to a plate on the wall to select your TV channel or start a DVD or a Video Cassette.
Mind you, what does complicate things, is the use of SCART leads, S-VHS leads and various other Audio things. [Linked Image]