Raffaello D'Andrea gave a really nice talk that introduces the basic concepts of feedback control using live demonstrations from his quad-copter research. The video above is the full talk as given at ZURICH.MINDS. If you want to see his quad-copters do one more cool trick, click through for the latest video of two pole-balancing copters tossing the pole back and forth between each other. The flying robots are great attention-getters but the talk covers some interesting and important topics, so it's worth a listen anyway.