It's not obvious at first in the video, but they pre-cut a flat base into the plum to stabilize it on the table, and are cutting in at a slightdownward angle. I feel like you could make nearly the same shot with a regular knife. Tricks like this (and the deliberate filming angles to obscure those details) make the video seem disingenuous and come across akin to a snakeoil sales pitch, which detracts from my genuine interest in how the ultrasonic tech fares.

The shot of the scale showing force as they cut through a tomato was more compelling. I notice after the initial breach, when the knife is about halfway through, the forces are equal again. I assume that's due (at least in part) to friction between the inside of the tomato and the wide, side of the blade. Do they make a skinnier vibro-blade, or something like an ultrasonic cheese cutting wire?

Ultrasonic cheese wire is an awesome companion idea!