Noisy Keyed Video
FAQ Composer Video Recording SDI Virtual Camera
Unfortunately it is the property of the advanced keyer that it emphasis the original noise in the footage. We will try to improve it in the future.
What you can do now is making sure that the noise of the original footage is as small as possible.
You can achieve this by leaving the "gain" setting in your camera on 0. (and/or decrease your iso) If the result will be too dark then you should compensate it by opening the aperture or adding more light to the scene.
Any suggestions or updates?