Your probably right about those spotters. I, for one though, wouldn't have any idea about how to go about spotting that much weight. Something I haven't considered before.
Hard to dissect exactly why he failed: he had good control after the handoff. Might be a bit off the wall, but it looked similar to something I've been known to do on my heavier lifts. Being left handed I sometimes overcompensate my right by making sure it's in exact position,as his is, causing a lapse in concentration. My left will sometimes flair out that way. Basically just overthinking the attempt.
Of course, having the barbell dropped on him afterwards didn't help things.