Cool trick, but it seems like since this is an aquarium forum someone should point out how the guy made a card with fresh permanent ink appear inside a tank (who knows if it was actually the same card or what). He then apparently pushed his hand into the tank to get the card back while the fish all cowered in the corner. Who knows what would have happened if the trick had gone wrong. I'm not outraged or ranting or anything, just pointing that out.
Also, notice the philosophical discussion going on in the comment section below that is 70-some messages strong about whether its ok the believe in magic. To me, that's more amusing than the actual video.