well that aiming technique is identical to wacthing a stereogram:
in this stereoimage you can see how the brain overimposes images that are not optically overimpsable like this and this \ /
the reason cause nobody can do what i do is that i see two guns while you probably see a useless fior aiming 3d image
in fact this aiming techinque allows to verify you tube is stereosocopic
use the aiming techinque to see the image double and wait for your brain to blend the images from two to a n stereo composition, the less you see them double the easier