Yet another reason I don’t work out in a gym.
Most of these aren’t fails in the sense this video probably means, but rather people deriving little to no benefit from the workout. Might as well not do it, then, especially if your atrocious form means you’re going to injure yourself eventually.
(And unless you’re doing shrugs, not doing the full range of motion of an exercise does just about nothing. Do the full exercise with less weight; it’ll benefit you far more even with low weight. Just do more reps.)