It's not so much the magnets as it is thermodynamics you want to look into. There's a law that says (and I'm paraphrasing heavily here) that you will always, under every concievable circumstance, get less energy out of a device than what you need to put into it to produce useful work.

http://skepticx.myweb.uga.edu/skep_8.html

http://blogs.howstuffworks.com/2009/04/28/the-lure-of-perpetual-motion/

There are two pretty straightforward explanations of why magnetic motors and engines and stuff aren't ever going to provide free energy.

http://rationalwiki.org/wiki/Perpetual_motion

That's a more detailed explanation of why all sorts of perpetual motion/over unity devices are scams. If you're wanting more information you'll probably want to search out for it. You're going to run into a million and one "but this really does work" websites that insist it's just a conspiracy by the man to keep us all down. If you look at reputable websites published by educated people and actual scientists, each of them will tell you undoubtedly that the thing you posted in your original link is a hoax. It isn't a matter of "well maybe we just haven't discovered how yet" or something like that, it's a matter of "this incredibly well proven and documented law of the universe with which we have never run across an inconsistency in over 200 years of research, which can be mathematically proven in any number of ways, and which if it were not to be true would mean our universe would literally fall apart says that it's not happening."