Unless I heard the expiration wrong (which is likely since I was half-listing at work) the original test was with light (photons), the second test was with seeming random atoms. But again I may be totally retarded.

 

The double slit experiment uses photons in each case, one unobserved where they behave as a wave, one observed where they behave as particles.



I haven't watched this video though so I don't know what it says. No sound at work.

 

The video is one of the more confusing ways I've seen it half-explained. I dunno why he's talking about using atoms instead of just a nice single-photon-at-a-time LASER. Unless he's trying to emphasize that photons are particles, but in that case the explanation sucks.

 

In terms of simply using photons, then the answer is hidden in what what he have yet to understand about light itself. His explanation sounded like a variation of the test using random atoms, and that is very simple to explain (see above.)