Here is a test setup of the Extron video system, consisting of an Extron System 7SC video scaler, an Extron TP T 15HD A transmitter, and an Extron TP R BNC A receiver.
The Extron 7SC serves as the video scaler, converting the input signal to the desired format. The Extron TP T 15HD A converts the video signal and sends it over CAT (5, 5e, or 6) cabling to the Extron TP R BNC A which then sends the signal over BNC connectors to, for example, a monitor or projector. The cable distance between the two Extron TPs can be up to 300m.
The test setup is a bit exaggerated, but is for demonstration purposes only.