THe earf is clearly concave & hollow.
This guy has a few more stunning video revealations, I think someone posted one here on BallGrab awhile back that was even better than this one I just managed to discover through the miracle of an intar-tube goggle search.
(Thanks, btw,, whomever was the BallGrabber that originally posted a link to that guy's vidya, I found it to be most amusing)