Bob,
They are probably using a video switcher and using the chromakey feature on it to produce the effect you are talking about. You however need a green screen that is properly lighted to achieve good results. I have used this technique during one of my daughters birthday parties…
the same technique is used for the weather channels…
In my setup, I had the second output of the video switcher connected to a dvd recorder. that way Idid not have to do any montage…
Robert
