Analog video presence detector is designed to monitor its primary video input signal and automatically switch to an auxiliary video input with the loss of the primary video signal. A captive screw terminal sub-module is provided for audio-follow-video capability for mono or stereo audio switching. A 3-terminal screw block provides dry contacts for normally open and normally closed to control peripheral gear. It can mount in a one rack unit frame that holds up to three 700 series units. A relay provides a hard by-pass of the primary video signal in the event AC power is lost to the unit. Front panel By-Pass and AUX Select switches allow to override the automatic change-over function and choose either video source. A front panel Status LED indicates the condition of the primary video input.