The hooks on the wall allow you to secure the rack at various heights between the ceiling and the floor. The first pulley (near the top left of first photo simply changes direction of the rope from wall to ceiling beam. The second and third pulleys create mechanical advantage/lifting for the left side of the rack (from this viewpoint), and the fourth and fifth pulleys do the same for the opposite side. After the rope goes through the black, freely-moving pulley, it goes directly to an anchor in the beam.
The rack itself is rectangular wooden frame with a taut cable fed through holes in the wood (like tennis racket strings) acting as the actual drying lines.
Check out Earthstead here: www.earthstead.co.nz.