Green Screen Usage - Wow, that's a lot of Green

This video is from the Stargate Studios Virtual Backlot Reel 2009.  Green Screen, or chroma keying, is a technique for mixing two images or frames together in which a color (or a small color range) from one image is removed (or made transparent), revealing another image behind it.  A common example is the television weather man standing in front of the weather map images.  This video shows examples of just how often Green Screens are used in television filming these days.  It's quite amazing to see what you thought was real is all just an illusion.