Originally Posted by AsianDivaGirlsWebDude

The green screen is called a chroma screen - they use it in TV/movies to knockout the chroma screen color and replace it with any background they wish. If you look at the video that was broadcast, they had an entirely different looking background.

EXAMPLE:

Sandy in front of the chroma screen...



Sandy with the chroma screen KO'ed, and magically transported to the Louvre Museum in France...



To put it another way. When you watch the weather report on TV, what is actually behind the weather reporter is a blue or green screen. They reporter then look at a monitor to know where to position their hands over the items they are pointing at, while reading a teleprompter adjacent to the moniter, so it looks like they are talking directly to the audience.

ADG