You have all seen this funny picture but lets use it as a “teaching moment” to show what your thought process should be during every exercise.
1) Safety first, ask yourself what could go wrong. Well, the precarious plates under my hands could start to wobble and fall to the side and its unlikely I could get my hands out of the grip holes fast enough. My fingers would get crushed and possibly broken and I might get a wrist injury as well. The two precarious plates might fall also and in that case I might hurt someone who happened to be walking by me.
2) Ask yourself what the goal of the exercise is. Strength gain? Balance? Flexibility? What muscle(s) are you targeting? Do you feel the exercise in the targeted muscles and nowhere else? I can only guess at this fellows thought process, I would guess he wanted to work pecs and balance at the same time.
3) Ask yourself if there is a safer way to accomplish the same goals. Working pecs and balance? Much safer to do pushups with feet elevated on a stable platform and find another exercise to work balance. Dance, Yoga, gymnastics, and martial arts all have lots of balance exercises that are safer than this.
4) Do a risk/benefit analysis and decide if you should do the exercise. Risk crushed fingers and busted wrists for a poorly designed balance exercise?