Zach King-like effect. PLEASE HELP!!!!!

So I'm sure plenty of people in here are familiar with Final Cut King/VFXbros Zach King.
Well currently, I'm working on a project where there is a a big gun fight in a room full of money. Aside from the muzzles, dust, etc. I plan on having money falling through the air. A while back I remembered seeing the video below. I have motion and know how to use it a little. I was wondering if anyone knew how to do that effect that he uses on the coulds how they bend and fold like that they are just peices of paper. That sort of effect is what I need so any help would be appriciated. A tutorial would be incredible.
Thank guys.

--Effect at 2:22--

Google "animating a waving flag in motion". I did that once and it might get you going. Don't remember exactly but I think an underwater-effect was used and tweaked (in addition to some other stuff).

Good luck!