[Christopher Loehrer] "I see that in Video Pilot's Tutorial about Keylight that he uses a .mov file. Is there any advantage to using that file over using a .AVI file?"
Depends entirely on what codec is contained in the MOV or AVI. Some codecs have chroma subsampling that limits the resolution of the chroma channels (the color in the footage, which is what you're using to key with) to 1/2 or even 1/4 that of the luma channels.
You can read more about this here:
http://en.wikipedia.org/wiki/Chroma_subsampling
Other than that and the standard compression artifacts there shouldn't be too many codec related issues with keying. You'll likely run into far more trouble if the footage was not lit and shot correctly.
Darby EdelenDesignerLeft Coast DigitalSanta Cruz, CA
