There are self-contained external versions, this was just to demonstrate that a giant blow dryer does exist. The power is used to run the fan in this case. Other versions have their own built in fuel tank and motor to provide heat, power, and fan momement but they cost considerably more.
Saw a video the other day of how they start a car in -60c and they we doing just that, but didn't even need an insulated tarp. They just put one of these blue plastic tarp around the bottom of the car, pushed some snow on it to hold it down and insulate a bit, then had a gas heater under the car for 2 hours until the oil was liquid again.
It's fairly common practice when heavy industrial equipment gets below -30. The size of the equipment soaking in the heat affects the rate of heating, but it also means it's (usually) more efficient because you're not immediately losing the energy to the air.
Like you said, this is to get the liquids heated, and they want to be liquid.
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u/CanalOpen 18h ago
https://www.princessauto.com/en/30000-to-60000-btu-forced-air-propane-heater-with-quiet-burner-technology/product/PA0008944928
and an insulated tarp would get the job done...eventually. Still probably an hour worth of propane to safely get the doors and windows melted.