OK I emailed Kuki with a bit of what is offered, lots of cruiselines.
Paul is correct with the site. (I dont know how exactly they do it except I do know its group cruises, and we suspect its the free berths on the groups but Im speculating).
You are added to already formed groups, and do not get a booking number and cabin assignment until the cruiseline closes out the group, near final payment time. So, its not for people who are not totally flexible, need special cabins and service.
So, I dont know how its done, but I know how it works from a pax point of view, and I can say its not for everyone... you have no idea which offers will come up next or what ports they will sail from.
Anyway.. Ill wait for Kuki before I say more. Paul said he looked and his eyes are rolling .. so that is why I thought I could help.
I do want to say .. the reason Im bringing this up .. I keep reading on here that you cannot get discounted Carnival or RCL cruises .. and Im here to say I have.