I'm confused, what's the difference between this and David's DVC rentals?
To expand a bit more on dansdad's fine explanation....
A common feature of timeshares is the ability to trade the use of your timeshare for a stay in another timeshare. This is called 'exchanging'. There are various companies that facilitate these exchanges between timeshares.
DVC uses RCI (Resort Condominiums International) to manage exchanges. So, for example, as a DVC member, I can use my points to 'trade out' to one of a number of other timeshares that partner with RCI, like, for example, Hilton's timeshare at Hilton Hawaiian Village.
It works the other way around, too. Owners of other timeshares that partner with RCI can trade into DVC.
What this company appears to be doing is reselling reservations that owners of other RCI timeshares have made at DVC resorts. RCI rules don't permit this, they do periodic checks for these resold reservations, and they cancel them if they find them. They don't find them all, but they do find some.
DVC by Request (David's company) only works with DVC owners, who are making reservations with their own points at DVC resorts. There's no exchanging involved, and DVC's contract with its owners specifically allows this.