What does a helicopter crashing look like?

A helicopter crashed and killed a person on the ground, and now some people are blaming the fact that the guy on the ground was wearing headphones.

I'm wondering if it's possible that he didn't realize the helicopter was crashing. I've never seen a helicopter crash, but I can't picture at all what kind of arc or shape the fall would take. I can sort of visualize the aerodynamics of an airplance, but not a helicopter. Was it obvious to the untrained onlooker that it was crashing instead of just flying low? Was it going in a predictable arc so you could see where it was going to hit the ground? Could you tell even if it was coming right at you? Is it loud enough that if it's coming behind you, you can hear that something's clearly wrong rather than just that there's a low-flying helicopter? How much time does it take for a helicopter to crash? Would he have had time to run away and would it have been obvious from its trajectory where he should have run to/from?

As a person who knows nothing about helicopters (yes, I've translated plane crashes, but never helicopters) I haven't the slightest idea what the answers to these questions are, so maybe it's possible he just didn't recognize that a crashing helicopter was out of control rather than just flying low?