I used to show an episode of American Rifleman TV in my training classes just to illustrate improper technique.

Some of the range shooting with the camera pointed back towards the shooter, you can see obvious flinches, they blink their eyes, dip the muzzle.

Yeah, this is sad.

This Managing Editor screws up the difference between the Marine 36 yard vs. the Army 25 meter zero procedure and states the setting incorrectly. To obtain a 300 meter zero at 25 meters with the M16A4, set the elevation two clicks (1 MOA) above the 300 meter setting. At 25 meters it should read 6/3+2, NOT -2. The ‘Z’ mark is two clicks up, not down. The M16A2 is in full minute clicks and should be set one click above 300.

The AMU Service Rifle team has a MUCH better video: