We have presented this video to the kids during our open days a couple of weeks ago at ENAC, Toulouse. It is just one application of a guidance algorithm that we have developed and later implemented in Paparazzi. I was actually surprised about the performance since the planes only exchange information once per second (even we allow some drops and the guys are still robust). I guess somewhere within next week I will write the "how to" in my blog, and together with code, people should be able to port it to other autopilots if they want to. Once it is ready, I will post it here too :P.