My wife has been watching a DVD lecture series on the Middle Ages and I have become intrigued by the camerawork. It is shot on a set, with at least two cameras. The interesting thing is the way the cameras track the speaker, who wanders back and forth while lecturing. The instant the speaker moves, the camera follows. There is no lag and no leading. The speaker is always centered on the screen. The movements seem too precise to be human, but the starts and stops are still smooth, not abrupt. Is there some kind of system where the speaker wears a transmitter so a motorized head can track them?
One system I know of for this hangs a small IR emitter on the talent, as part of the microphone. Robotic cams with an IR sensor can track that point. Such systems risk being too sensitive and feeling very "ping-pong" like.
If a computer is hooked to the camera it can use pattern recognition and motion tracking to notice when the picture changes and track towards the direction of the bigest moving object which would be the talent.