Anyway, the point is that these TV cameras are based on the fact that incoming light will dislodge electrons from a thin plate in a vaccum tube in an amount proportional to brightness. A very bright spot in the image produces a shower of electrons that is more powerful than the rest of the tube (the part that detects the electrons) can deal with. The net result of this "splash" of electrons is a mild desensitization of the detection apparatus around the bright spot. This makes the nearby stuff appear darker.
You mentioned that dark spots also seem to have a bright halo, but I don't see that in the video, and it isn't consistent with the usual artifacts of these cameras. Are you sure?
There do seem to be subtle halos around dark spots, though. See here: https://youtu.be/1LwkljjLBns?list=PLelIK3uylPMFHC6Xny11XFXgw... It's not very noticeable in a still but is pretty clear when his hand shadow moves.
Example: https://upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Us...