He has 3 lines, a skyline to hold the load up, which is in this case tensioned and tied off. A haulback line, tied to the pulley (carriage) on the skyline, with another pulley below it and belayed on the portawrap up top where the debris to be moved is. Finally the mainline, which goes through the bottom pulley and clips to the load. The pulleys are positioned roughly above the load, and the mainline is pulled out and tied on the log. When he comes up on the mainline, the load goes up to the pulley. By easing off the haulback line, the load will creep down the skyline, but if he lowers it too much the load will hit the ground, so he has to pay close attention to the height. When the load is at the landing they simply slack the mainline.