Brandie you are spot on about the too literal thing, and i knew it when i heard the requirement; I thank you for your time in adding to my question here;

As a programmer, I started thinking about how this would be done without a hardware fix, and here's my theoretical idea:

Programs like Remote Desktop, Terminal Services, Skype, goToMeeting, TeamViewer, GoToMyPC, PCAnywhere(still around?), etc all do a variation of this already; it's Video sharing or keyboard-video-mouse(KVM) sharing.

so a theoretical modification of some similar software could be built, dunno if there would be much of a market for it though; but it's an interesting exercise.

The idea would be i would need to "call" the presentation computer, ie like Skype does or something, and that caller would already need to be trusted in some way.;

so that presentation computer's version would be an always on listener, and that automatically disconnected the current "caller" and automatically displayed the ""latest" caller's video feed, where the feed is the current desktop/primary screen.

possible, and in a few hundred man hours, i could probably do something like that myself, but that's not gonna happen.

Off the shelf software, or it doesn't get done in this case, i think.

I'll google a bit more, but i don't think software like that exists.