What if Zapruder hadn't filmed the assassination?
How would it have affected our knowledge of the assassination? Would the Single Bullet Theory have ever been developed? I have my doubts although there would be a dilemma for the finding that there were 3 shot and 3 hits, 2 on JFK and 1 on JBC. Why were there only 2 bullets recovered if three had struck the victims. Maybe somebody would have developed the theory but it would be much more difficult to support.
Of course other people were filming but none showed the shooting from start to finish and none had the vantage point Zapruder did.
What other mysteries would we now be facing if not for Zapruder?