The proof is the fact that in the Zapruder film at frame Z133 we see the typical lightening of the frame which only occurs when a film is stopped and restarted. Anyway the fact that Muchmore did the same thing only highlights the fact that you don't waste 8mm film when you only have bugger all.
Here are the first two Zapruder frames centered on the blue car after Zapruder started filming, with the initial frame being lighter.
Rubbish. There is very little over exposure there at all. Fail Mytton. Note the difference in the light color of the road way in Z132, and compare same to Z133, which according to Mytton is lighter, because of that's when Zapruder allegedly restarted the camera.
If you want to see frame overexposure compare Frame Z001 to Z002.
Btw I don't want to waste any more bandwidth with your bait and switch, either deal with the evidence as presented or go and make up some more backyard photo claims.
JohnM
Please yourself, but don't make up things which you wish happened, but didn't.
It is you who should deal with the evidence not invent things.