this sounds like some personal trainer who just got his latest and fanciest certification. he has his clients do things on those phsyio balls and very slow movements. I've seen one of the guys I used to work with do that. If he was training you, you'd be using 3 lbs. for laterals and extensions, 1 plate per side for everything from squats, presses, to deadlifts. his clients look the same all year, every year.
just like any of you who've been at a gym, and one of the trainers, who looks like complete shit, comes up to you and critizes what you're doing and gives a suggestion.