The video shows a rotating camera at the top of the car that's scanning for objects (I guess). What's the advantage of a mechanical rotary movement over an array of cameras that give a continuous 360 degree view (e.g. the street view cars)?

Update : Found a link : http://www.pcmag.com/article2/0,2817,2402516,00.asp In an interview last week, Stuart Woods, the executive vice president of Velodyne, which manufactures the LIDAR (Light Detection And Ranging) rotating module that sits atop Google's autonomous vehicles, said that his company has started developing prototype security systems that could be trialed within the next year. The Velodyne LIDAR HDL-64E and HDL-32E modules use an array of either 64 or 32 lasers to electronically "see" the environment, Woods said. On Google's car, the module is set inside a rotating drum. Its lasers complement Google's own mapping software and GPS data, which help orient the car on the road. The LIDAR provides additional positional data, but also identifies other cars, bicycles, pedestrians, and road hazards.