Not an expert, But familiar, son is expert. Ok so the build @3:00 is a generator,pumping station. The doors allow acces to install equipment/maintenance. Those are 8 inch exhaust stacks (silver) coming out (notice rain covers on tops). So 8 inch exaust x 2 each on of those can support close to 1000 hp. Just saying maximum . So we see the pipes coming in from ground level, thats water, In or out. posibly both, but cooling those powerplants (both) would only require 2 pipes,1 in (cold) 1 out (hot) This is a pumping station. The generaters(could be a single monster caterpillerV8) run electrical power for the island but 1000 times bigger than needed for power only(i will confirm engine/size with friend /expert) . This is a pumping station capable of serious (20,000 plusGPM)possibly more. I did NOT see fuel tanks, they would be big,real big. 50>100 GPH depending on load.   They are pumping water out of somnething underground. Pumping it in, would not need very much water, even a desalination plant would not need this much power. For how many residents? Plus there are no water storage tanks that I can see. IMHO we are looking at a D.U.M.B, with deep water access.I have not watched the rest of the vids so dont be too hard on me if I missed somthing, I have only seen this one.