The secret to this trick is simple...and kind of brilliant - Genii Online

Here's the thing about magicians: they lie. From the moment they step out on stage until the last round of applause ends, they are lying to you. You, intelligent member of the audience that you are, know this, but what you might overlook are the many different ways they're lying to you. As this video from Richard Wiseman elegantly illustrates. 

You can't even trust the furniture when a magician's around.