VGA Splitters

Perhaps a personal experience of mine can help you out.

Certain video drivers allow you to split displays on two screens to two locations. A little bit of a personal experience - I had a Lenovo 2000 C300 where the monitor went bad on me; a friend was nice enough to give me a monitor so that I could work properly.

I then managed to get my previous laptop, my Compaq Presario CQ60-211DX to work and boot properly. Out of curiosity, I decided to hook up a VGA cable to connect my laptop and my monitor. It allowed me to have a dual-monitor styled setup, which was awesome for showing people things (it's an ideal presentation setting!).

If you have a VGA splitter, that would mean you're able to connect to three things, no? If I'm not mistaken, VGA connections work by adjusting the overall monitor length (or width, if two different resolutions) to split amongst multiple monitors, which is why you can carry windows/programs through multiple screens on a multiple-input setup.

With what you are asking, though - you'll be able to have a dedicated screen for the contestant, but you'll have to be the one to control it.

EDIT: oh, I just thought about something. If you're the one on the presentation monitor, perhaps you could set it up in some sort of really funky way where the host has control of what they click/touch/choose/whatever -- alternatively, if you are using touch screens for any reason (doubtful), then you would both have control!