That’s BNC it’s typically used in professional set ups for broadcast or general video production, can send hd using sdi over shorter runs but once you get a couple hundred feet out you have to down convert. It’s my understanding that you can use nearly any old coax cable if you put a bnc head on it.

Very common connector for decades of broadcast and consumer gear.
BNC, 75 ohm analogue video only input and output.
BNCs could also be used for RGB or YUV signals in which case there’d be three of them, labelled accordingly as R G & B or Y U & V (or Y, B-Y, R-Y) or, later, serial digital connector which would carry digital video and 2 to 16 channels of audio in which case it would be labelled SDI.
The supplied picture shows an analogue, video only signal on what looks like a consumer device such as a VCR.