I don't think there is any special trick to it -- it just occasionally pops up and if you're in the right place at the right time, asking for the right dates, it gets offered.
People have reported sporadically over the years getting offered great deals -- better than even AP rates -- just on the phone. It seems to be a little less rare this year, with a few reporting it.
Here's my theory. Think of it like plane seats. Airlines hate unsold seats. The plane needs to fly anyway, so even if they could only get $20 for an unsold seat, they would do it. The problem is, they can't routinely sell their unsold seats for $20, because then lots of people wouldn't buy the $400 seats, hoping to get the $20 deal.
So how do you deal with this problem if you're the airline or the hotel industry? Well, on way is with priceline or consolidators. Make the ticket a little less attractive or increase the level of uncertainty. This way you capture the discount market without really chewing into your base market. Disney traditionally has done this with codes -- specifically targeting them and limiting the number. I think the problem is that the disney going public has become much more aware of codes and so it's starting to swing the pendulum the other way -- undercutting their rack rate business. So they've been flexible -- instead of codes, they offer
free dining. It allows them to keep the rooms at rack, but give away an item that costs them relatively little.
Sporadic random discounts like $200 at the yacht club is, I think, the new wave. They have already sold enough rooms for the summer that they don't need to do codes, but they still hate to see 8 percent of their rooms unsold. So this is a way to get a few more sold in a way that people won't rely on. Now, if people are canceling other reservations to make these, it doesn't work out. But maybe that frees up inventory for rack paying customers at other resorts.