I'm not a scientist, but it looks like as he pedals forward, the air catches the little scoops and rotates that drum. It must be connected to the rear wheels to give an extra little boost as it spins up.

stick a windmill on your car. it doens't speed up your car and this wont speed up his bike.

it's just a flywheel...i'd say little assistance is coming from the wind and more is coming from the angular momentum (rotational inertia). I bet it is harder to get started than a conventional rickshaw. If you want to know more check out: http://en.wikipedia.org/wiki/Flywheel

It looks like he was trying to build a cross between a bicycle and one of these:
http://videosift.com/video/Can-you-sail-downwind-faster-than-the-wind

Unfortunately, I don't think that green drum he's using is doing anything as a propeller.

I can't quite make out whether or not he actually has the drum connected up to his axle, that black strip running next to the green support bar might be a friction belt?

Even if it's not connected he could still get two benefits from having it fitted:
1) A psychological placebo-like effect, due to his belief that it helps.
2) An increase in the number of customers he can attract, due to standing out from the other rickshaws.