I think the confusion is based on two things:
1. The technique of heaving-to. Most of us probably got the basic concept as a set of instructions (tack the boat through the wind without shifting the jib, letting it back, then lash the tiller to leeward or towards the mainsail). But heaving-to is defined as "using any sail combination, any gear combination necessary to get your boat to lie stopped, about 50 degrees from the wind and drifting slowly, directly away from the wind behind its own slick" (Storm Tactics
, Pardey and Pardey, p. 13). The method that the video narrator describes is his method of heaving-to.
2. The concept of the slick. Again, based on Storm Tactics, the slick breaks up waves in bad gales, which will help protect the boat. In fact, Storm Tactics is pretty much a dissertation on how and why you should heave-to in gales vice running, lying a-hull, or any other basic storm method. They made a believer out of me.
Annnnnd this post just became an advertisement for Storms Tactics. Here's a link to it: Amazon.com