1963; PRESIDENT KENNEDY, WHO DONE IT? ZAP VS AI VS MAFIA VS CIA OR ALL

William Robert Greer (September 22, 1909 – February 23, 1985) was an Irish-born agent of the U.S. Secret Service, best known as being the driver of President John F. Kennedy's presidential limousine in the motorcade through Dealey Plaza in Dallas on November 22, 1963, when the president was assassinated.
The video

The 90-second clip comes from a longer 1991 interview (archived here) by then-KUTV news anchor Bob Evans with conspiracy theorist Bill Cooper, who died in 2001. In this segment of the interview, they talk about Cooper's claim that Greer shot and killed Kennedy as he was driving Kennedy in a motorcade on November 22, 1963, the day JFK was assassinated. Cooper, a former naval intelligence officer, said he had access to top-secret documents in that role. This is what he told Evans at the 1:43 mark:

Cooper: The documentation clearly said that the assassin was the driver in the car in which he [Kennedy] was riding in Dallas on that day and it was plainly visible in a film with help from the public.

Evans: Now you brought that film with you. Let's take a look at that, if we can. Here's the film. Go ahead and narrate that for us. Will you?

Cooper: Well, it took me 16 years to find this film, because it has really been withheld. And what you're seeing here is the motorcade on Elm Street, passing in front of the book depository building. Kennedy has been shot in the throat and Jacqueline is pulling him toward her, trying to comfort him, and she's in shock. At this time, you see the driver turn around with a pistol in his left hand, firing over his right shoulder, and shoots the president directly in the head. ...

Watch the driver, his name is William Greer, he was, in fact, a Secret Service agent.

Zapruder film

The film described in the video and the portion shown in the Instagram post is known as the Zapruder film, which was shot by Abraham Zapruder as the motorcade drove by the Texas School Book Depository. The Dallas clothing manufacturer set out to record the visit by Kennedy but instead chronicled his assassination.
https://leadstories.com/hoax-alert/2023/01/fact-check-john-f-kennedys-secret-service-driver-did-not-kill-former-president.html