So just slip of the feet and nothing to do with any loud gunshot just heard yes?
I don't know what caused the Wiegman stumble/fall. Wiegman is looking back over his (L) shoulder as he ran forward, so he could have stepped into a chuckhole in the grass, or a rock on the ground, etc. When Wiegman did his piece with Gary Mack on, "Unsolved History JFK, Death in Dealey Plaza" (2003), he specifically mentioned feeling the "compression" of a bullet on his face. I thought he was referring to a point in time immediately before he ran across/down the Knoll. But, we are talking about only seconds between his feeling the "compression" on his face and this Bell Film snippet showing him stumbling/falling. Wiegman detailing this "compression" on his face was recorded 40 yrs after the JFK assassination. This is the only time that I am aware of that Wiegman mentioned this bullet "compression".