The window is about 18m up. The distance to the x is approximately 60m. This is a 16 degree declination on a moving target. The target is moving left to right at approximately 30 degrees away from the depository at 25mph. That is not an easy shot. The grassy knoll is approximately 40m from the pint of impact with the target at the same elevation and coming almost straight in.
No, ever been there? It is not a head on shot from the grassy knoll. I have been there 20 times.
And there is a group of experts from Australia that duplicated the shot. The very first time they tried it from a perch with the correct height. I have been in the window next to it. It is not that much as a deflection.