One picture was taken every day at the same time. The timer was set at sunrise on the shortest day of the year. In this video the suns motion is not caused by the rotation of the earth. That was eliminated by the clock which took the picture at the same time every day. Here the motion of the sun is caused by the earths orbit around the sun and the inclination of earths equator with respect to the plane of earths orbit around the sun. This is the first seasons timelapse that actually shows the cause of the seasons we experience here on earth.