It is a much simpler easier to build and probably more accurate solar compass.
The video shows a solar compass design. It is based on equatorial mount. Equatorial mount is an axis parallel to the earth's axis of rotation and lines up with north/south and is used for telescopes to point at the sun or stars all day with constant rotation. In this case, you do not know exactly where North/south is but you use the other details of the equatorial mount equation to find that line.