The National Review explanation was just painfully and obviously stupid. The video demo was rather poor and lacked the obvious expertise that the demos linked in post #47 has.
What was stupid about the National Review explanation? They are just presenting a fact: the PDF creation process creates layers and visual artifacts similar to the ones that birthers point to as evidence of forgery.
Why would National Review defend the validity of the certificate if they didn't believe it was real? They clearly don't like Obama and want to get rid of him.