The "coke bottle rocket" has been around since about the first day that "coke" was carbonated. The propellant is essentially the same as used in old-fashioned soda-acid fire extinguishers. With CO₂ dissolved in water, any change in pH (acidity) will cause an effervescent release of gas. Since the gas has a larger volume when free than when dissolved, the pressure in a closed container, or one with a restricted outlet, will rise, and expulsion of the liquid provides the "mass transfer" needed to propel the container.

A very similar "device" is frequently used to demonstrate the propulsion principle for kids in "rocket clubs" (a.la. "science classes" for pre-teens) but better control is usually achieved by using plain water and a small air compressor (with a pressure guage) to pump up the gas.

Pressures obtainable by "CO₂ effervescence" are relatively modest (seldom more than the pressure in your auto tire, and less than in some bicycle tires) unless extreme confinement is achieved. The same CO₂ is confined in the original "coke bottle" at a pressure that the container can withstand easily enough, and shaking the bottle releases some of the gas at about the same pressure as can be obtained chemically. The difference is that the chemical effect can continue to release a larger volume, rapidly, to sustain the gas pressure as the liquid finds somewhere to go.

The "incident" in the video is an obvious demonstration of stupidity, but is considerably less dangerous than if the photographer had been trying to capture the "star's" curve ball, and the "pitcher" missed. Even an "amateur" can throw a lethal baseball, but the "rocket," while perhaps a little more massive, lacks the 60+ mph(?) velocity capability to be much more than embarrassing.

Kids need supervision and training (much more of both than is common) to play baseball, and "experiments" of the kind shown should be supervised.

Unfortunately, there's less that can be done about adults who swim in the scummy parts of the gene pool. The only effective recourse sometimes available is to leave the vicinity immediately whenever you hear the familiar "Hey, Bubba - Watch This!"

(Remaining to watch indicates that the scummy part of the pool is perhaps too close to your own comfort range(?).)

John