It's a switch.
I use them all the time connecting vcr's, etc to my HDTV.
Here's a link to a 3 way a/v switch I found on the evilBay (link)
There's a ton of them on there.
Here's the same thing from another site (link)
You really only need a 2 way, but one of those 3 way switches would give you an extra input if you ever needed to add some other input device.