A friend of mine followed that boat under a bridge the first time they did it, running from a serious storm and heading for a hole. Jay took pictures that ended up in a number of magazines. The crew were thoughtful and careful. If you look carefully you'll see a number of control lines on the bags. Those guys definitely knew what they were doing.
It is indeed a metaphor for the TV commercials that say: "professional drivers on a closed course." Not for those who don't really truly understand the forces involved and the angles at which they are applied. Like so many things that require skill, those who can do it well make it look easy.
I've watched those a couple of times and always wonder about the halyard chafing and possibly breaking at the top of the mast with it being pulled so far off to the side like that. I'd be needing an adult beverage (or three) after going under the bridge for the first time.