These flying thresher designs show up every now and then. They supposedly have some sort of aerodynamic advantages, but it's not clear what they are since they never seem to make it out of the lab. Here's the latest, from the University of Maryland.
From the video description:
Cyclocopter utilizes cycloidal-rotors (cyclorotors), a revolutionary horizontal axis propulsion concept which has many advantages such as higher aerodynamic efficiency and maneuverability. One of the key advantages of the cyclorotor is its thrust vectoring capability, which is utilized in the present study for yaw control. The present vehicle has a twin-cyclorotor and a horizontal tail rotor configuration where each of the rotors is powered using independent motors.
The cyclorotor design was optimized based on the detailed experimental studies conducted by Dr. Moble Benedict, Mr. Tejaswi Jarugumilli and Prof. Inderjit Chopra. A novel attitude control technique is developed using differential RPM control and thrust vectoring of the cyclorotors for rolling and yawing, and horizontal tail rotor for pitch control. For closed-loop attitude stabilization of the vehicle, a proportional-derivative controller was implemented on an onboard 1.5 gram processor-sensor board. Using this control system, the stable autonomous hover of the cyclocopter was successfully demonstrated.