Where did the white car come from?

Probably from behind, swerving right trying to avoid the van.

I think he was traveling in the same direction as the truck and swerved left to miss the motorcycle and that put him in front of the truck.

The car’s momentum carries it mostly forward, and only barely to the right.

I think it was alongside the motorcycle, and was trying to race or catch him.

I agree with @filmfann , but both the car and bike were at fault and the bike didn’t even stop.
Their light was very red.

Looks like the car and bike were racing.

I think the white car was making a left turn into the intersection at speed.

I agree with @filmfann it came from behind up on the left of the camera

I can see that now guys.

Who makes a turn at that speed, on a red light?

That’s the problem. The box truck not only appears to be making a u turn, but it is making the turn not from the inside lane but somewhere from the far left of the screen. Notice the position of the truck’s left headlight as the sequence begins. Our view of the scene is apparently through the windshield of a vehicle stopped for the visibly red light. Check out the angle at which the car crosses in front of the motorcycle. There is no way it might have been paralleling the bike prior to the intersection. The bike clearly ran the light at considerable speed. I think the white car was turning into the same direction of travel as the motorcycle.

It was in the left lane, next to the motorcycle. Not sure if they were racing or if they were doing the speed limit. With a 4 lane divided highway, the speed limit was probably 55 or more. But they both blew the red light.

I don’t know the answer to this question but the motorcyclist is one lucky SOB.