Assuming the Zapruder Film Was Altered, Part 2

Noel Twyman’s book, “Bloody Treason” shows good evidence for the Zapruder film being altered heavily. For instance, the driver Greer turns his head 2-3x faster than is humanly possible. The alteration is likely meant to hide, among other things, that Greer brought the limo to a complete halt during the shooting, while the Z film shows a steady slow speed of the limo. This fakery was probably done by super-imposing the limo image onto a moving background. Now, if we assume this was done, we really can't trust the Z film for any info about where the limo was when JFK was shot. Thus, all these careful, "scientific" analyses of assassination shot angles, are meaningless: For instance, the grassy knoll was ruled out for the fatal head shot here, because the angle was wrong. But if we don't know where the limo was exactly, then we don't know the angle of the shot from the grassy knoll.