Does anyone else notice at the end how the smoke starts to turn into a shit ton of sub smoke circles moving in all different directions, spaced nearly perfectly apart??????
Vortex rings.
A vortex is fluid rotating around an axis (also has something known as vorticity). Vorticies have to follow a couple of rules, and the one that’s probably relevant here is Helmholtz’s Second Theorem, which simply states that a vortex tube cannot end in a fluid; it must either end at a surface or form a closed path. In the case of smoke rings, the vortex tube closes in on itself to form a torus.
(img from Wikipedia)
As you can see, a smoke ring is essentially a ring of rings all spinning about.
So what happens when two of them collide? Well, in the ideal case, where the two rings were of the same magnitude and opposite in rotation, they’d hit each other and…stop. Each would have an equal effect on the other and we’d have a stagnation point. Which would look bizarre, but also really cool.
Alas, the real world is often different from ideal physics, and you’re pretty much almost never going to get that. There’s going to be some variation somewhere, which means that the two rings will break up as seen here. But because of the smoke particles, you can see the dissipating, evenly-spaced bits of vortex tubes.
A Middleground 