Well, you may also wonder how he even walks with no knees, but considering he can use his feet to operate the mouse for a mean game of Quake, I'ld bet he is pretty limber.  He can probably do all kinds of amazing "feets" with his feets.  He probably just stands on one foot and uses the other like a hand with really short fingers.

Many years ago (1980's ?), on "Ripley's Believe It Or Not," I watched a boy with no arms solve a Rubic's Cube with his feet.  He and his brother, who had arms, would race to see who could do it with their feet the fastest.