The original article is about a UAV that masses 20 g, whereas the links you mention have video from a Funjet, which is has a mass of 550g, according to this: ht

The original article is about a UAV that masses 20 g, whereas the links you mention have video from a Funjet, which is has a mass of 550g, according to this: http://www.barnardmicrosystems.com/L4E_arctic.htm#x3 http://www.barnardmicrosystems.com/L4E_arctic.htm#x3 So, that's 27x the mass -- a completely different problem in terms of engineering.