The footage is grainy and the gnat/mosquito flying across looks extra white probably because of the night vision tech inside the security/surveillance cameras. The amount of dark smoke might be causing the camera to be erratic adjusting for what might be day or night.

It's the simplest and most reasonable explanation. Suggesting it is extra-terrestrial spacecraft is silly since we rarely catch clear unadulterated video footage of such a thing. Most footage of UFO's is something that could just as easily be a fly flying across the damn screen.