A multi switch is a device used with a dual or quattro LNB to distribute satellite TV signals to multiple (usually more than four) receivers from a single dish and LNB.

Multi switches are commonly installed on or in blocks of flats to allow all the residents to receive satellite TV without having to have a separate dish for every resident.

Also you can connect the multi switch to your cctv system and you can see the cameras on all TV that connected to the multi switch.