How to rig a windsurfing sail. 

At 2:37 the line was threaded in the wrong direction in the sail-pulley. The lines will line up much nicer when it is threaded in the same direction for all the three pulleys in sail, i.e. from the inside (near the mast) to towards the outside . This is peculiar for the Severne RDM extension, while their SDM extension works better the other way around.