I saw the documentary mentioned above and I agree, it does convince me that the injuries sustained by the occupants of the car could have been caused by bullets from the book depository.
But all that tells me is that a gunman from the book depository could have caused the injuries.
It by no means proves that Oswald was the gunman or that he acted without anyone else knowing about it, let alone anyone supporting him. I'm sure the documentary makers would agree, since their focus was purely on the gunshot wounds and where the shots that caused them could have come from.