Thanks to the miracle of crowdsourcing, we have a definitive answer to Vanessa’s question about a film taken in the presidential motorcade on November 22, 1963. It was taken by JFK’s aide David Powers.
Powers gave the three-minute film to the Assassination Records Review Board in 1996. The film stops well before the motorcade reached Dealey Plaza because Powers’ camera ran out of film.
Here’s a CNN story from when the film first surfaced in 1996.
Thanks to everybody who provided information.
Here’s the film itself.