Where did it come from?
Look at its front tires.
I'm trying to. The headlights shine on the front tires and the whole car. The car has a shadow on the front as well.
'Ghost car' is perfectly forward/beyond the one that is in front of the camera car and then it abruptly turns left in front of it. Its sharply-turned front tires give it away.
... acceptable answer, but it is the true one. The C-Class (ghost car) seems to be running the light, coming in from between the trolley and box-truck waiting to go the other direction. Due to the position of the 5-Series, most of the car is blocked, but if you look carefully, the rear lip of the Mercedes and some of it's taillight are visible as it enters the junction. The red car to the right of the BMW notices the Mercedes first and applies the brakes much earlier.
Video is bullshit. there was a local urban myth in the town where i grew up. Supposedly, if you where driving down hill at night, a ghost in an old car where start tailgating you until you got far enough away.
is that the one where the police cam was chasing a car and the car disappeared thru a metal fence?