Sometimes you see a technology which looks like magic. Happens all the time in security, more often in IT, not so often in real world.
Steorn, for instance, just demonstrated Orbo, its new free energy technology. Violating one of the core principles of (not so) modern science. However, the demo itself was nothing worth of note. It's the tiny, small quote at the end "next week, come and try: measure with your own equipment".
The trick is not showing some magic. It's having people actually use it. It's one of the oldest techniques in the world, and made fortunes in IT (remember? Shareware). Any product has to learn from that: put down the barrier, release "easy to try at home" products, have people see for themselves. A video won't do it, nor will a live demo. OpenSource developers (including me) should learn it.