Apple Photobooth recognizes a still background and then replaces it with another background. It works like a Chroma Key, except for the fact that you don't need a green screen. The big problem is that I don't have a Mac and even if I had one, I wouldn't be able to export it to a movie and edit the background manually.
So, can I use a similar technique to key a video? The camera doesn't move and I have an image of the background besides of the recording itself. What can I do?