A system that displays a video signal on a display for a computer system is presented. During operation, the system receives a signal to switch from displaying a video signal from an internal video source to displaying a video signal from an external video source. In this system, the internal and external video sources are coupled to a bi-directional video port for the computer system, wherein the internal video source generates an output video signal and the external video source generates an input video signal. The system then determines whether the external video source is coupled to the bi-directional video port. If so, the system couples the external video source to the display and determines whether the external video source is a valid video source. If the external video source is a valid video source, the system displays the video signal from the external video source on the display.