I bought this and, well, you said it perfectly. It's not a hard trick to do, but it will take much practice to get it to a performance level and even more to get it as smooth as Chris'.
But really a revolutionary idea behind this trick, and it's absolutely and totally impromptu. If you don't mind putting lots of practice into great effects (which a magician should not), this is certainly worth the $5.
At first I was kinda disappointed, because I was distracted while watching it, so I somehow missed a crucial step, got frustrated and gave it up altogether, but then I went back and watched it again, and raelized it's pretty cool.