How not to perform a rep on a bench press.

The adult there allowing this to happen is, uh, questionable.

He should start investing in a wheelchair.

Where was the rep?

You're supposed to bring the bar down to your chest, not your belly button up to the bar. This is just advanced yoga.

Former powerlifter here, In some powerlifting competitions, this could be considered a full rep. Some powerlifting shows only require your feet and shoulders to be planted, so a lot of competitors on the bench portion arch their stomach like this.

Yes it looks weird and not a normal rep, this is only done in powerlifting meets.

He did all that and didn't even lift it, they helped him. Is that how people lift now with their back arched ? I've seen that posturing before and thought it was weird.

Diogenes once plucked a chicken and held it up yelling "Behold! A man!" making fun of the definition as of man as a featherless biped.

This I feel is simular. "Behold! A bench press!" as I guess you could define this as one but it really isn't.