Abraham Zapruder

Abraham Zapruder was a man who filmed John F. Kennedy's car as it traversed the Dealy Plaza.

One version of Jenny had seen Zapruder's film from a version of reality where Kennedy's assassination was successful prior to changing history in one universe by shooting the would-be assassin before he could take his shot. She knew that in this reality too, Zapruder was shooting his film, which would obviously turn out to be of much lesser historical value. (PROSE: Fragment: Guinevere and Mordred)