The filming of both deaths.... If there was a nefarious plot to kill both these men (and I believe that at least Oswalds execution was entirely organised). Then we have the lone gunman, the member of the public, publicly killing the victim. This sounds rather basic but what it does is prevent any discussion of Kennedy being bumped off behind the scenes in a coup, assassinated by Putin or Oswald being silenced by ' them' for what he knows. Obviously the Z film was released later but the execution was conducted in public and actually the Z film could have always stayed in the bank as a back up, albeit edited, to be released in a time of need by the conspirators.
Oswald had to be killed on TV because he was never going to be in public again and so his mysterious death soon after the crime in private would have been incredibly suspicious, even to the general public ( who in those days could still largely think for themselves) . The transfer was the only time it could be reliably done, other than the media press conference, which of course Ruby attended, gun in pocket.
it really was a show, performed and scripted.