Look again, carefully. The second line of images on the composit shows the man described as the ginger haired white man with a receeding hairline. He's the one holding the gun in his white/RIGHT hand. I doubt he shot anyone. He's the one holding what looks like a black stick in his left hand. He has white shirt cuffs, and is proably the one with the gold cuff-links.
Now look down at the gap between the seats, there's a man there dressed in black, with a black cap covering his hair. That might be who fired the fatal shot. You have no idea of the timing - the video starts far too late. What is missing is what was going on ON THE OTHER SIDE OF THE WINDOW.