DIY Single-Channel Television
It might be easier to buy a small handheld TV/ display that accepts NTSC, tune it to the channel (or hook it to a cable box / tuner tuned to the right channel), and then simply turn the power to it (or the video feed) on and off by some controller that handles the caller-id condition.

If your'e a programmer by trade, this is likely the easiest way to solve the problem, maximizing use of off-the-shelf parts.