When I was on the VDB list on ORD-EZE back in May, I asked if my Premier status would escalate me on the list, and I was told no. But the agent said that she would keep me in mind, and I got the bump.

So it is still a mystery whether it is status or time placed on the VDB list.

My experience is that gate agents sometimes take volunteers without seat assignments, before clearing volunteers from the VDB list. Finally, party size also has a big impact and has caused me to miss out on a few bumps.

Still, I am not complaining. I think the best approach is to not bother the gate agent, except perhaps one gentle reminder if you are placed on the VDB list at the ticket counter.

Also a similar question....does anyone know what criteria agents use for creating a VDB list? It is routine for a flight to be booked > capacity, and it won't be known til the 20 minute cutoff whether there aren't enough seats. So what is the threshold for predicting an oversale? (Flying out of hubs this applies much less, because most people have checked in much earlier.)