Actually, Walter Cronkite was mistaken on a detail. He said the Warren Commission concluded that the first shot was fired at frame 210. And the last shot at frame 313.
While their were some involved in the investigation that thought the first shot occurred at, or shortly after frame 210, some disagreed. While their may have been a small majority (I think) of the investigators who thought the shots were confined between z210 to z313, there was enough doubt to give no definite scenario in the final report. They said there was a shot around z210 and z313 but the other shot could have been before z210 or between z210-z313. This was a wise decision.
In the sixty years since then, with more analysis of the Zapruder film, there is now a general consensus among LNers that the:
* first shot: hardest to pin down, but may have been around z152 (my view). In any case, well before z221.
* second shot: universal consensus that the second shot was at z221-z225.
* third shot: universal consensus that the third shot was at z312-z313.
However, the general consensus among CTers is, well, there is no general consensus among CTers. No CTer has ever come up with a compelling scenario, even among just their fellow CTers.