David Healy on the Z Film Alterations & 1963 Tech--2003 ZAPRUDER SYMPOSIUM

Healey says the film is altered; Costella says it was manufactured wholecloth.
https://rumble.com/v6r5fa6-dr.-costella-uncovering-the-probable-techniques-used-to-alter-the-zapruder-.html
https://rumble.com/v6r58ia-zapruder-film-alteration-techniques-pre-dated-1963-by-35-years-greg-burnham.html (very short demo of other video productions)
Mantik vid OTW which also gets into the "How" & its history.
AI summary of this David Healey presentation:

***David Healey's 2003 Presentation***
"David Healy's presentation at the 2003 Zapruder Symposium, titled "The Zapruder Film - Is Seeing Believing in the Assassination of JFK?", focused on the technical aspects of film alteration and the technology available in 1963. Healy, an expert in the film and television industry, aimed to counter the myth that the technology and expertise required to alter the Zapruder film did not exist at the time of JFK's assassination.

Healy addressed several key points:
-He refuted the standard argument that there was no time to alter the Zapruder film, providing insights into the film editing techniques and equipment available in 1963.
-He explained why the first-day copies of the original Zapruder film were made on 8 mm film rather than being bumped up to a larger format, suggesting that this was a deliberate choice to facilitate alteration.
-He discussed the background magnification in the film, which he established as an illusion, and provided a detailed explanation of this proof in his chapter of "The Great Zapruder Film Hoax".
-He emphasized that the purpose of his chapter was not to analyze the content of the actual film but to demonstrate that the technology and expertise to alter it were indeed available.

Healy's presentation was part of a broader effort to challenge the authenticity of the Zapruder film and to provide a technical foundation for the arguments that the film had been altered to obscure the true events of JFK's assassination."
sources:
http://www.assassinationscience.com/johncostella/hoax/healy.html
https://truthandshadows.com/2013/12/10/the-faking-of-the-zapruder-film-and-where-the-magic-bullet-really-came-from-an-interview-with-jim-fetzer/
https://www.imdb.com/name/nm6960981/