Oh, boy. You are years behind the information curve. Have you heard about the group of Hollywood film experts who have identified numerous indications of alteration in the Zapruder film? Have you looked at David Mantik and Doug Horne's presentations on clear, compelling evidence of alteration?
Here's just one indication for you: In the Z film, the cloud of blood and brain matter disappears far too quickly, impossibly quickly. Tests have proved that this cloud should have remained visible for at least six frames, but it vanishes in less than two frames. That is physically impossible.
Totally false. The cloud we see coming off the head would never last that long in the film frames with the 15-25MPH wind speed that was blowing in DP that day. The wind blew the matter to rear, onto Hargis, Martin--plus they rode into to it, and some of it landed on the trunk lid. The majority (heavier) matter went forward all over the car, the Connally's, Greer, Kellerman, the windshield, the sun visors (both sides of the right visor), the hood of the car, the side rails and the interior, and not to mention what would have landed in the street. Skull fragments from the top pf President Kennedy's head landed several yards away, SW of the car at the time of the fatal shot, and these were picked up by 3 different people. Seymour Weitzman, David Burris,, and Billy Harper. The Burros and Harper fragments were turned over to the authorities. The Burros fragment was shipped in a small Neiman-Markus box to Washington and given to George Burkely. These skull fragments can clearly be seen flying high above the limousine at the time of the fatal shot, at a speed of 80+ MPH, according to Dr. John Lattimer. The speed can be calculated by viewing the Zapruder film. The same fragments can clearly be seen in high contrast, clear prints of the Orville Nix film as well as the Marie Muchmore film, which coincide with the Zapruder film.