This traces back to the timeline of the Darnell Film. It shows Officer Baker running across The Island. The timestamp for those images of Officer Baker is currently accepted as being :20 seconds after the kill shot. Prior to that, the Darnell Film's opening frame shows the driver of Camera Car #2 standing flatfooted outside of his camera car #2. This clearly indicates that all 3 camera cars had been standing still for an extended period of time. Certainly longer than the :20 second timeline attached to Officer Baker running across the Island. Wiegman jumped out of Camera Car #1, and ran down Elm St. He filmed the JFK Limo going under the Triple Underpass. With all 3 camera cars being at a dead stop, a dead stop that was so long that that the driver of Camera Car #2 vacated the vehicle, means the filming of the JFK Limo being on Elm St was far longer than the Zapruder Film leads us to believe. This means the JFK Limo did an extended "rolling stop" or a flat-out "Stop" on Elm St. Extending Officer Baker's currently accepted :20 second timestamp on the Darnell Film also places his confronting Oswald inside the 2nd Floor Lunch Room to a later point in time. There are other dominoes also falling as other timelines are properly put into place. This ALL started with the Hi Definition Opening Frames of the Darnell Film being released by the Sixth Floor Museum. I believe that the Darnell Film Hi Definition revelations also reveals why NBC has Never released their Original Darnell Film or their Original Wiegman Film.
The opening frame of the Darnell footage is less than 20 seconds after the headshot.
At the time of the opening frame Weigman, is filming the Hesters.
He finishes filming around 17 seconds after the headshot.
Four or five seconds into this footage we see Weigman running down the knoll to where the Newmans are.