Flush the disk cache.
After Effects V. 126.96.36.199
Premeiere V. 7.2.1 (4)
Operating System: OS X 10.9.1 (13B42)
Processor: 2.8 GHz Intel Core i7
Memory: 16 GB 1333 MHz DDR3
Graphics: AMD Radeon HD 6770M 512 MB
Quicktime: V. 10.3 (727.1)
Source footage - Filmed on a Canon 60D
23.976 fps, 1280x720 Not sure of the native codec
It's too bad it was shot on a DSLR; they STINK at precise color reproduction. Oh, it's good enough to fool the human eye, but not a computer. It's not the imaging chip that's to blame, but rather the codec in which that stuff is recorded.
But if your main complaint is with noise in the blacks -- a common problem with Keylight -- I use two layers. First, I pull a good key using Keylight, and I go by the Status setting: white at the core, grey on the edges, don't worry about the green tinges in the white. The key is right. I set it to Final Result. I don't CARE if it looks a bit noisy: I know it's right.
Then I duplicate the layer, and reset Keylight. This time I go for spill suppression on the lower of the two layers. I know that I have it when the chroma key background goes gray, and status shows me that Keylight isn't creating any transparency: it's totally white. It's also very tricky to get to that point.
Then I use the upper layer as an Alpha Matte for the lower layer. Voila! A nice-looking key with no noise. If there is a spot with fast motion, I look at the blurred edges for any of the chroma key color. If I see it, I tweak Keylight on the lower layer.
If the edges don't look very good, I tweak the Keylight settings on the upper layer.
You don't often find a simple, one-click-and-you're-done solution to keying. It often requires masking, and a whole boatload of layers to build the entire image before you're ready to say, "Now, that's a good-looking key."