if you rewatch that angle, you'll actually see the WR yank on his helmet immediately before this screenshot, so he was readjusting it. Not a great idea, but he wasn't unbuckling his helmet in a nonchalant move, but more, that it was jarred in an uncomfortable way.
Do yourself a favor and find the UCF play-by-play. They go from very flat, matter-of-fact calling of what they think will be the last play of a pretty massive choke, to absolutely losing their minds.