Loc: Seattle area, WA
Allan, thank you for posting this. There is much to be learned by watching a professional play, even if she is not my favorite pianist. To me it's especially interesting how she supports those loud bass notes - either using a chopping motion with the side of her hand or using more than one finger.
I had the fortune to stand next to a concert pianist/teacher as she demonstrated those very notes. At first I was skeptical that someone so slender could deliver the necessary power to make those notes ring but she produced a bell-like quality that was deep, rich and loud enough to shake the rafters. I could feel my pulse rising as she become louder and louder. She too used the side of her 5th finger.