The above video features models of perpetual motion machines that have been suggested over the centuries. I assume that the makers of the video resort to trickery to make it seem like the machines move without any energy input, since it is a fundamental claim of physics that a perpetual motion machine is impossible. (Physicists believe that energy is always conserved, and any machine like this would have to lose energy through friction.)
Indeed, the impossibility of perpetual motion machines has even been encoded in law, in that patents cannot be granted for such a machine unless a working model is provided.
Nevertheless, over the years various people have claimed to be able to get more energy out of such machines than they put in. Read some of the fascinating stories at this site on perpetual motion machines.
For some modern-day examples, see below the fold:
An Irish company named Steorn claimed to have made a “Free Energy Generator” that would produce more energy than it consumed. It’s a perpetual motion machine. Naturally there was a good deal of skepticism, so in 2007 they decided to put on a demonstration.
It didn’t go well.
Read Ben Goldacre for more details. (You should be reading his blog anyway.)