Most younger chiropractors now use a miniature "jack hammer" (I think it's called an applicator) to avoid breaking a patient's back or at least avoiding a massive lawsuit.
There are still a lot of "old school" chiros out there who do the same thing as this guy.
If I want to stretch my spine out (like this guy is trying to do), I simply grab on something with my hands, get my feet off the ground, and let gravity pull downward on my spine.