Not sure how you can make this conclusion based on the Vermont study. I haven't seen the video but looked at the study itself - here it is.
The study was never designed to determine how much calorie intake is going to result in a fixed amount of weight gain or to determine whether there is a limit to weight gain. It didn't do appropriate controls in order to research that (such as control the anxiety levels, activity etc.). It was designed to study the mechanisms in by which the body stores new weight and also how it gets rid of excess weight (their weight loss was controlled as well.)
Their input was rigorously controlled (being prisoners), and their exercise regimen was pretty easy to monitor and control. Most of them gained weight, but almost none of them nearly as much as the standard "3500 kCal is a pound of fat" Standard Model would predict. Several plateaued on weight gain, and a few lucky (?) prisoners were *never* able gain 10% of their body weight when eating nearly 10,000 Calories a day. Simply couldn't do it.
Wrong! Pretty much all of what you write here:
- all 5 subjects gained weight just fine as expected
- the amount of weight gain per calorie intake was never measured
- nobody "plateaud"
Go read the study for yourself!