You have 2 magnets positioned so that they repel each other. (Yup, just like a spring.)
(Keep in mind that "force" is not "energy". Remember the formula for Work? Force times Distance? W=F*D.)
I apply a force with my hand. (That alone does nothing.)
I apply a force with my hand and push the 2 repelling magnets closer together.
I have added some energy.
(The energy is stored as Potential Energy and it is the same type as a compressed spring and also the same as when a weight is lifted above the earth. "Adding Potential Energy" means they move from a lower Potential Energy state to a higher one.)
The magnets push back at me, but I don't let them move. (This alone is just force, not energy.)
The magnets push back at me and I allow then to move. As they move apart they give up some Potential Energy. ("They give up Potential energy" means they move from a higher Potential Energy state to a lower Potential Energy state.)
The energy provided by the magnets as they move away is the same as they energy they gained as I pushed then together. The energy released can be used for something. It can even be used to push another pair of mangets closer together. (Without the help of my hand.) But the total energy released is never more than the total energy supplied at the start.
Now in a different set-up, I have a bunch of magnets arranged in a circle and a spinning wheel and some more magets that are stationary. Some are pushing and some are pulling. The Potential Energy between any 2 magnets chages as the distance between them changes. (The Potential Energy between each pair might be increasing or decreasing) There is some (Rotary) Kinetic Energy of the spinning wheel. (It has mass and is moving.) It might be speeding up or slowing down.
How do you calculate all that to prove that something special is happening or to prove that nothing special is happening???
From watching a video? You can't prove anything. if you build it yourself, you'll know for sure. If you had the exact design, you could do a whole lot of calculas and know for sure, but that's a lot of work.
You have a tool that will disprove every questionable device that you see. That tool you have is simply the knowledge that it can not be. It not that we don't want those devices to work, it's just that we have learned enough about the universe to know that they don't.
No overunity device can exist. This follows directly from the Laws of Thermodynamics. Those laws were not invented, they were discovered. And so far they hold. (And I know this has been said before, but.....) "If they are ever found to be in error, it likely won't be by some guy spinning wheels in his garage."
Feel free to watch the videos and enjoy the show. Some are lame. Some are quite entertaining. Steve posted a link to something entertaining. It's all tricks. Sometime you can figure out the trick. Sometimes you can't figure out the trick, but you still know that it is a trick, simply because it can not be.
-timothy48342
Oh. And those pictures with the magnets and the lines? It's a visual aid to help imagine that shape of the magnetic field. Nothing is traveling or being transfered along those lines. If you added a picture of a compass, you could draw the compass with it's north-south beam alligned with those magnetic field lines and that would not be too far off from real life.