>Right below that mark will be a small window in the floor.
>In case of a cockpit gear indication failure, one pilot goes back, peels back the carpet over the window, and checks the manual alignment indicator in the wheel well.
or http://airplanereading.org/story/4/loss-of-blood-flow
The co-pilot and flight attendants were trying to lift up the carpet in the exit row, apparently to find a floor window which would give a view into the cargo hold. No such luck. The carpet had recently been tacked down to the floor when this particular aircraft underwent some renovations. Unfortunately, no consideration had been made for the floor window in case of an emergency, such as we were presently experiencing.
It's unlikely that the pilot simply took a gamble. Presumably ground crew took a look, either on the first go-round or during the second approach, and confirmed that the landing gear was down. I like to think my "screw it we'll see what happens" IT methodology isn't used in all industries...