Your VCR is hooked up to your TV (coaxial into the VCR and from the VCR into the TV). Just before the broadcast starts, you press the record button (which was often mechanically linked to the play button). When it’s done, you press stop. Then you rewind and can play it back later.

The end user is sort of passively recording it. The broadcast happens regardless of the user’s or the VCR’s presence.