Greetings,
Sensitivities about this vary from JW to JW. Of course some magicians like David Blaine(sp?) cultivate an aura of "dark power" as a source of their tricks while others like Penn & Teller reveal straight up that it is only a trick.
The Society in its usual way has made various statements about magic and the supposed relation to the occult and also as we know in the past "magic" was a word used very broadly to include all kinds of stuff from chemistry to occultism to spiritism and practices that would be considered strange for a christian such as voodoo & santeria, etc. Things like this lead most JWs to reflect the official Society antagonism towards all things called "magic" and of course this even bleeds into many other areas such as Harry Potter, etc.
However, I say that sensibilities differ because some JWs will perform a card trick or other kind of trick. - Not to mention or include the "separating finger illusion", "got your nose", "pretending to throw something and dropping it behind your head" or any kind of "shell game" all of which are tricks of a sort and which probalby everyone has done to someone (usually a child) at some point.
I was once at a congregational picnic and a brother showed me a great card trick, which I have used on a number of Witnesses myself and there were certainly no objections made, however, I will say that he was quick to disclose how the trick was performed. I think JWs who do perform any kind of card tricks or other kinds of slight of hand tricks, etc. would be quick to follow up with a revealing of how it is done specifically so as not to cultivate any kind of implication that "magic" was involved.
-Eduardo Leaton Jr.
PS: As for David Copperfield, I saw his show once and I had a seat on the very back row high up on the balcony. He was making this woman disappear and I just happened to get a glimpse, from my angle, how she jumped back and ran very low behind a wall about 2.5 feet high or so.