The video below shows a sneak peak into the workings of the annual Bernkastler Ring Riesling auction.
The bidders at the front of the room are brokers acting on behalf of clients who have previously instructed them to bid to a certain price. Once the highest bid is reached, the brokers confer, as pictured, and agree to split the lot between them according to their clients' wishes. This video shows the final lot being auctioned, a TBA Riesling that goes for significantly more than its estimate!
You might spot the maker of that Riesling, Markus Molitor, sitting to the auctioneer's right, next to the current Mosel Queen, complete with tiara.
(My thanks to fellow MW student and multi-linguist Anne Krebiehl for her help with the translation.)