We put them out to make people think it is only nutters that think perpetual motion machines work. If you want to prove one of these energy machines works, it's easy. You pour some water in and start the water splitting machine running. The water is split, using electolysis, into hydrogen and oxygen. The electricity that is produced by the generator is used to power the water splitter.
Surplus energy is used to power any electrical appliance.
The water never runs out. The easy way to demonstrate this is to power a small light bulb or some sort of household appliance. If the machine keeps running day after day, and keeps a bulb alight, then it works. I could tell straight away that the machines on the programme didn't work, because they weren't continuously lighting up a light bulb. When a PMM works, the inventor demonstrates it working.