Ok, this is an ad and is not. Is an ad because it was conceived like one, and is not, because it wasn't made by the company or the advertising agency... but just by a guy and his partner.
Nevertheless, is a great ad, that has all the potential to become viral. Check it out following the instructions... Believe me, once you have seen the surprising ending, you will want to check if it was an optical illusion or just a camera trick.
It is an optical illusion and you can verify that by seeing it again without following the instructions, just checking the end. The whole thing is simple but a GREAT idea!