Bet you any money they are model aircraft, by the looks of it, probably rigged with lights and a stabilizing gyro, the can hover on their prop too to account for the stationary periods, all pretty quietly with an electric motor, the duration was said to be about 20mins thats about the endurance of most electric R/C models. There was someone saying there was a buzzing sound like a motor who was close to them. I live right near a model aircraft field (around 1km) and they are maneouvering just like model aircraft look, however at night. I have seen some kids rig up literally hundreds of LED's on some the look pretty impressive!
theres even a haeap of videos of people doing it on you tube however closer than the UFO video
YouTube - RC Night Flying UFO