Uncharted 2 - Skip for part of chapters 19 and 20

This is a pretty long airwalk that skips the end of 19 and the beginning of 20. I was watching PotatoHandle's run of this game at the time, compared the two, and this was like 33 seconds faster.
You actually have to mash d-up pretty fast for this one or you'll end up too low. I alternate between fast and moderate speed so my little arm doesn't get tired.

My path is kind of confusing so feel free to find a more simple one. This recording is the first time I actually got the skip to work.
Still, this is where I go:
You need to start the airwalk from as high up as you can, so I go off to the side at the beginning and then start the airwalk. Notice where my grenade line is aimed around 48 seconds in. That's the direction I want to end up in.
Keep going that way until the grenade is pointed at solid ground (Look at the arrow at the end of the line around 1:31 in)
Then start moving forward and right. At 1:41 the grenade passes over a little wall. I stop moving to the right here.
Eventually the camera will get locked off to the side (It's supposed to be a platforming section with Tenzin) and the area will load in. If you mashed fast enough, you should be able to land in the next area. Normally the tank busts through the wall here, but I was able to skip that.
The rest of the level works normally for me.

[AKheon]

Nathan Drake threatens the gravity with a grenade, and so it yields.

[mmarc]

This game :D Someday you will start airwalking in chapter 1 and stop it in the boss fight or so :D

[arthurjacquemin]

Are you on PS3 or PS4 ? I don't remember this glitch.