History:
Take a careful look at the machine and why it's located in a huge safe. Finsrud's Perpetuum Mobile gets it's energy from ultra low frequency seismic vibrations from earth. The earth is never perfectly silent even if we cant feel it. Just look at a geological seismograph readings, there are always small background vibrations present. There is nothing fancy here and it is possible to create a setup without a moving ball to generate a minute amount of electricity directly. His huge safe removes local higher frequencies coming from local sources like local car traffic, and leaves the ultra low frequency from deep in the earth to sync with the mechanical ball's speed. This is why it doesn't always work. Those springs which the ball occasionally hits off the pendulums actually act as very efficient 1 way diodes, like in a boost converter. Or, the machine is like a huge AM crystal radio, except, not electromagnetic, but, mechanical vibration powered.
Probably, a huge mass held on a horizontal beam in the air, where part of that support beam is one of those efficient mechanical crystals like in the BBQ spark ignitor, with the other side secured to the earth on a huge slab of heavy concrete will probably generate a tiny measurable AC voltage/current due to it's change in bending from earth's vibrations. This can also be done with good old fashion magnet/coil like in some older seismograph measuring instruments.