Sergei came to the Drones & Aerial Robotics Conference (DARC) in New York City to demonstrate his fotokite, an autonomous quadcopter tethered on a small dog leash. He explains that by constraining the robot with the leash, he is able to simplify the dynamics it has to deal with. The robot is programmed to maintain a set angle, and effectively hovers at the end of the leash. A camera mounted on the robot provides an effect that is a cross between an airborne pet and a steady cam.
This was one of my favorite moments of the conference.
More details on Fotokite here. Sergei tells me it's a PX4-powered copter with custom code.