Your problem is you don't have a clue as to how to weigh evidence.
Let’s see. On the left side of the scale we put 20 witnesses (there are at least four more including Zapruder, Clint Hill, Bobby Hargis, and Linda Willis) with different vantage points all saying JFK reacted to the first shot. On the right side we put Glen Bennett (his second statement, not his notes) and
your feelings about what you think you are seeing in the zfilm. Hmm. Which way would the scale tilt?
Your continued blind faith in eyewitness accounts demonstrates that. You think because a witness tells you something, it becomes an established fact.
Drawing conclusions from 20 witnesses all saying the same thing is not blind faith. Blind faith is your belief that your interpretation of the silent zfilm is more likely correct than 20 independent recollections. Can you point to a single event in history where 20 independent reports of a simple observable fact got it wrong and zero reported it correctly?
By the way, if you think that an independent witness cannot corroborate another witness, you are wrong. You should also review your high school lessons on probability and statistics.