A YouTube post claiming to show a muzzle blast in the JFK assassination from the second window of the pergola in frames 20-22 is nothing more than a lens reflection (https://www.youtube.com/watch?v=XLERm5sKGSY). Here are the frames:
The so-called “shot” is on the right side in the second window of frame 21 (outlined in red):
As you can clearly see, the lens reflection also appears on the grass in front at the same time (outlined in red).
Both reflections are gone in frame 22.
Here’s a gif of the three frames:
You can also easily see two more white spots directly above the supposed muzzle blast in the window in the gif. Nothing more than reflections going on here.