Top Reddit comment:

Honestly, a lot of psychological warfare is bullshit. He says you want them to say no because they feel safe with no, but then he says you want them to say yes because you're more likely to get another yes. Each one of his statements sounds justifiable on its own, but when you mix them, none of them work with each other. So essentially, nothing he says is going to work most of the time. And I don't mean "he doesn't know how to manipulate people," I mean he says a lot of stuff that has worked to varying degrees over the years, but not a single one of his tips are going to guarantee someone does something you want them to. It's also becoming more known that psychological studies are not the greatest at producing a verifiable results. If I say a certain chemistry experiment works, other scientists can try to replicate that in a lab, and if they can't, then I'm wrong. However psychology studies are published all the time that fail when tested independently.

http://smithsonianmag.com/science-nature/scientists-replicated-100-psychology-studies-and-fewer-half-got-same-results-180956426/

Also:

The SOP that the FBI (and other government agencies) use for these types of crisis situations is the Behavioral Change Stairway Model. Crisis negotiators are trained to "run the staircase" in order to end the situation peacefully.

Reddit comments:

https://reddit.com/r/videos/comments/4xx5kr/in_negotiation_getting_a_no_is_actually_better/

https://reddit.com/r/lifehacks/comments/4uvhis/in_negotiation_getting_a_no_is_actually_better/