With respect to possible alteration of the Zapruder film, the removal of footage showing the right side of the JFK limo turning onto/heading down Elm Street would qualify as an alteration to that film.
Dear Sonderführer Storing,
https://www.marktyler.org/mc63.html?fbclid=IwY2xjawK4zONleHRuA2FlbQIxMABicmlkETFFODdsRHVIa2RSUGZJNllFAR6Zx-0JB5zBmwy-qakJKtfLfY5vcW9V2IqOrNXjP-oezkHhb-av38NlRUa-uA_aem_2d95NRPz2dpt6k_03l7iYgThe three “Lead Motorcycles” we see turning onto Elm Street from Houston Street and passing by Zapruder in Z-132 are being ridden by Stavis Ellis, Leon E. Gray, and W. G. Lumpkin.
As Zapruder was filming Ellis, Gray and W. G. Lumpkin navigate the turn from Houston to Elm and ride their motorcycles past him, the Presidential limousine was a block away from the intersection of Houston and Elm, turning onto Houston from Main.FWIW, the aforementioned three "Lead Motorcycles" were preceded about ten seconds earlier by five “Advance Motorcyles” ridden by Bellah, McBride, Garrick, Freeman, and Brewer. These five “Advance Motorcycles” weren’t “captured” by Zapruder because he hadn’t yet turned his camera on.
What's more important for purposes of our "conversation" is the fact that about 80 yards behind Ellis, Gray and W. G. Lumpkin on Houston Street was the DPD “Lead Car” driven by Chief Curry, and about 50 yards behind it was the Presidential limousine.
Although Ellis, Gray and W. G. Lumpkin were “captured” by Zapruder, he didn’t “capture" the aforementioned “Lead Car” because he had turned his camera off at Z-132 to save film.
Factoid: It took the Presidential limousine about seventeen seconds to get from the intersection of Main Street and Houston Street to where we see it in Z-133, some seventy feet down Elm Street and heading towards Zapruder.
D'oh!
-- Tom