The behind the scenes tells enough: [youtube]http://www.youtube.com/watch?v=MUWvQXhZopM[/youtube] Just keep the legs straight, not bend. (control by feet, not knees)
This is actually the second vid about this type of thing. Devin filmed water jet packs before, and it was actually posted on the forums here. [youtube]http://www.youtube.com/watch?v=im1iNq02Kz0[/youtube] Devinsupertramp is generally a great channel if you want to see awesome stuff. You've probably seen at least 3 of his vids without knowing (or with if you actually know him ofc). Things like trike racing, the human slingshot, and puppy Christmas are his. He basically gets paid to fly where ever and film awesome things that people do.