Have you ever felt how light a bird is? Hollow bones et al.
Have you noticed how big their chest muscles are?
You'd need ludicrously huge muscles, like cartoon levels, to come close to flying like that vid.
I want to tie a rope to the front of a windsurfer and attach it to the ground. Walk downwind, preferably over something soft like water... yeah, you know where I'm going with this. 
You know that there's a big battery pack and servomotors in the wings, and the chest muscles are only providing like 5% of the total power, don't you?
You windzzzzzurfers are lagging behind the kiters as usual 
www.seabreeze.com.au/forums/Kitesurfing/General/Dutch-guy-makes-wings-out-of-kite-materialflys/
