I've used it once to get tickets, but I never actually flew with the tickets because the times I could go were blocked/out or already booked by other people (I did get a full refund back and with no hassle, mind you).
It works like eBay, yes. You look and see if you like what's for sale and then put in a bid and quantity (sometimes it's for a pair of tickets, sometimes its per ticket). If you win, you get the tickets/vouchers.
Even when I tried it once before I had my (pun not intended) reservations. Sometimes they only say "a major airline" as opposed to telling you exactly who you are flying with. That phrase is the same reason I swear by Priceline for hotels but never for flights. I want to know exactly who I'm flying with.
A friend of the friend who first introduced me to the site a few years ago swears by it. Neither she (my friend) nor I have actually had success yet with the site. All I can say is I was all set to use it and had the tickets worked out, I would have.
On the other hand, depending on where you are, flights to and from Orlando seem to always be on the cheaper side. It may be worth a try for skyauctions, but remember the going price on tickets regularly. I don't remember if they have reserve prices like eBay, but make sure you don't bid yourself out of your price range.