With these Lightning Deals you only have 15 minutes to claim them/checkout or you lose them (and more often than not you're completely limited to only one copy per customer, which is a good thing). So, if people take too long deciding what they really want, that could be another way for them to lose them and for someone else to claim them.
I guess the lesson here is don't abandon the site if Amazon tells you you've been put on the waiting list because you might get the deal after all.
As for the DS set, it's now at 48% with more than an hour to go in the sale...