I wonder why they don't use ducted rotors... (or why all drones don't use ducted rotors; would the increase in weight offset the potential for increased thrust?) I think I originally saw this video here on badweb:
I'm surprised it doesn't have a bumper cage surrounding the rotors. That would make all the difference between catastrophe and simply bouncing off of an obstacle that you'd drifted too close to.
I think the tolerances for a drone sized duct would be problematic. I've worked with ducted fans in side model airplane fuselages, but once set up, it's pretty well protected. On a drone, they are hung out on the corners and going to take a beating. The easy solution is to fix the duct to the propeller, but the will greatly slow down throttle response, hurting performance and sucking battery power. It will probably make more sense on a full scale set up where your would be able to build it strong enough to survive normal handling, but would certainly want to avoid the kind of tumbles that are pretty routine with small models. Just kind of guessing though.