He explains how to tie a "blood knot" and what the blood knot is used for, which is joining two separated rope/string ends. He demonstrates the knot, which starts by taking the two lines and lining them up one on top of the other, so they are parallel to each other. Then, start winding one end around the other, at least 3 or 4 times. Do the same with the other loose end as well. Then, place the first end through the wound part of the two ropes where you started. You pass the other end through in the exact same manner, only it must be threaded through in the opposite direction of the first end. Finally pull both ropes away from each other, tightening the knot. The two lines should be bound together pretty tightly now.