As HCS said: "... rejecting the ordinary and finding refuge in the extraordinary".
The followup responses to the video show Commager's prescience.
It's been more than half a century since the Warren Commission issued its report. Since then we've had followup investigations by the government directly into the assassination, i.e., the HSCA, and indirectly, e.g., the Church Committee hearings. In addition we've had numerous investigations by major news media such as CBS and PBS, ABC, the Washington Post, et cetera. And other investigations by independent reporters. Add to this the works of people like Robert Caro who has spent more than twenty years studying LBJ's life. Other major figures such as Hoover and agencies like the CIA or SS have been reported on, e.g., Tim Weiner on the CIA. Toss in the tens of millions of pages of government documents that were released.
And all of those subsequent studies and investigations and works support the WC conclusions that Oswald alone killed JFK. Yes, the HSCA said there was "probably" a conspiracy; but that was largely based on now discredited police tapes. And yes, there are still some ancillary questions about how much the CIA was watching Oswald and whether they were delinquent in warning about him, e.g., Joannides and the DRE.
But the response to all of this fifty plus years of study - the assassination is the most studied event in America history - is, as Commager predicted, dismissal. These are simply, to the conspiracists, examples of more coverups and evidence of more conspiracies. In conspiracy world there's always a conspiracy going on to prevent the exposure of the original conspiracy. And every investigation that determines there was no conspiracy is responded to by saying the conspiracy continues and ANOTHER investigation is needed.
And one note on the Warren Commission: the claim that Earl Warren (??!) ordered or signed off on a coverup is ridiculous. Who did the coverup? The staffers? And then they stayed quiet for the rest of their lives? Rankin and Redlich and Specter and Liebeler and Belin? Some are still alive: Willens and Slawson. So they continue to this day to cover up what happened? It's just an example of what Commager said: conspiracists only have one response to the evidence that Oswald killed JFK: the evidence that he did is evidence of a conspiracy!