On the right (far) side of the wood-and-rope bridge are two small movable platforms connected by ropes. Jump to the lower one, and then to the upper one, and you can get close enough to jump left to...
first get to the top, (climb up the waterfall) then run down the hill to your right. Jump up on the platform hanging from the line. Jump up and to the right of the platform, and you should be able to...
Get the glider he gives you after you give Leo his notebook and glide to where those wooden bridges and stuff are with that man standing there. You'll see a medal there and pick it up. You need the...