As great as this video is, it occurred to me that people who normally use green screen for shooting would have a problem going through the breakdown of their green screen setup, and redoing everything to get this effect.
I asked Curtis if he was okay with me using his video as a reference, and he was fine with it (nice guy).
So I created this video.
Although I show how to do this in Premier Pro, it's simple enough to perform in any video editor.
The steps are simply a.) pull your green out of the shot, b.) add a white background (or any background of your choosing), and c.) yank the luminance setting on your keyer down to zero.
The "math" here is once you key yourself out of the the layer, you are now the only thing that is emitting light, and by removing all the light (luminance) you now are a silhouette.
Pretty simple technique, and by tweaking the other settings you can come up with some interesting effects.
The Basic Filmmaker