Read the comments posted below the actual video....
Plenty of theorys.....
Pipes adjacent to grooves in wall = Cooling inlets evenly spaced, complete coverage to cool a massive "coil" that was (judging by your footage) an experiment in anti-gravity. This would have been possible using "round" objects "within" a field. Likely spinning! Suggesting that "ufo" is a laymens reference to something mysterious above the ground. This would have been in a category of propulsion research. The tunnels, imo look like a way for a barracks to swarm an invading force. Otherwise you have too many blocked up at a doorway waiting to get mowed down as they come out. Why swarm? To give the Nazis a chance to protect secret research. The town was a cover for the research facility. The mine was the cover for them being underground. The power plant was meant to divert suspicion as an implement of a mining community.