Any high-jumper, long-jumper, tripple-jumper, gymnast or trampolinist will tell you that correct arm motion is essential to optimal jump height. It's a biomechanical fact... and quite obvious if you think about it.
Though I thought DK was joking to be honest. The flappy, flailing of arms of the panicked n00b, indeed does little to improve jump height.
Please don't get Lukman started on this. He's convinced that you can jump with just your arms. No leg or ankle movement at all
(and I don't mean during a handstand). He's so weird... he's awesome
lol.
But yes, arms make a collosal difference to jump height.