If by “rapidly” and “quickly” you mean “in a lot less than an hour” then OK.
Liquid propane can flow out of a tank for a remarkably long time, depending on the temperature, aperture size and tank construction, and as @Bonivus_elderheart noted, in the video it looks like that’s what’s happening at the point when the tank is kicked. Note the flareup as the liquid is sloshed out of the hole!
Before it can expand into a gas, the liquid propane has to take up heat (PV=nrT) and this is not at all instantaneous. If you release the valve on a large tank, you will see ice forming on the steel as all the heat is forcibly sucked out. As that steel gets colder and colder there is less available heat and the process of liquid/gas state conversion slows down, and the pressure drops at the outlet. Eventually the outlet can even ice shut once there isn’t enough internal gas pressure to blow off the ice. If you are burning the released gas very nearby, this of course provides more heat and prevents icing up, but it takes measurable time for the heat of the burning gasses to be transferred to the liquid remaining, so if there’s a large volume of liquid it could take ten minutes or more to convert it to gas.
There’s a table of vaporisation rates based on temperature and wetted thermal transfer area here.
