I'd be quite interested how he meets the power requirements, is he using electric dryers? I feel like a vans alternator has no hope of running 1 let alone 2 of them. Also what does the freshwater/wastewater system looks like?
The video also talks about external connections for power and water if it's available.
That said, he could easily have a generator rigged up to supply power. A lot of RVs have on-board washers and dryers, so the technology is widely available. If I were going to do something like this, I'd try to find dryers that heated with propane both for efficiency and to limit the electrical draw on the generator.