There's some show that pops up on cable every now and then (on the FX channel, I think). It's this "magician" in a mask and the whole show is him basically spilling the beans and showing how some of these Copperfield type tricks are done.
What amazed me was the fact that in so many of them, the audience was INDEED in on it, and it was meant to play to the TV crowd.
Other times, it was simple misdirection and optics (tricking the eye with perspective, angles, distance, etc.). The misdirection is just ages-old slight of hand work.
Funny thing is, now when I watch a magician (especially a lower-rung, non-pro type), I'm watching everything BUT the trick. Doing that, I've caught many of their "moves".
If you know what to look for.
However, Copperfield and Penn and Teller and others will DEMONSTRATE that, THEN proceed to totally blow it out of the water and STILL do the trick after showing "how it's done"...and the trick is 5 levels beyond the standard version of it!
I STILL don't know how Copperfield got those two guys on the couch to levitate. Then dropped them into that glass, walled area, sealed it up and still made them float. We'll probably never know. But rest assured, it is an illusion. And chances are, it's way more simple and "of course!" than we probably imagine.
For him to do that stuff with a 360 audience is pretty cool, because on that "Magician's Secrets Revealed" show, SO many of the tricks hinged on the audience being in the standard "front of the stage" position. In other words, LOTS of the tricks involved stuff going on BEHIND the box/tank/cage/etc., out of the audience's view.
With a "stage in the round" set-up like Copperfield had on his show the other night, that takes that completely off the table!