What is the most efficient way to run downhill?

Today's question for Ask Coach Parry comes from the Coach Parry Facebook group and with it being a down run at Comrades this year; many runners are asking this question - What is the most efficient way to run downhill? Is there a trick to it?
Coach Parry answers this question and talks about things you can do to minimize the damage in your legs during the race as well as different things you can do during training to prepare yourself to get stronger for the downhills.