Green screen, the process by which directors can map any image behind on actor to make them appear to be in a place too fantastic or expensive to visit, is normally thought of in terms of action films. The fantasy and sci-fi genre relies heavily on green screen and CGI to fully realise a vision by those that make TV and film (it doesn't always work, granted). However, green screen is far more prevalent than you might think. For example, did you know that Ugly Betty is filled with CGI and green screenery? Here's a video for all you technerds out there. It's very interesting.

Stargate Studios Virtual Backlot Demo from Stargate Studios on Vimeo.