I don't know what's wrong with helicopters in Brazil, but they keep crashing them in the most idiotic ways possible. Check out this rescue helicopter going a little bit too close to the water until it finally crashes against the waves. Thankfully, nobody was hurt. [Bing]
There is no engine noise at all as the helicopter comes in — it was autorotating with no power. You hear the beachgoers' voices but the helicopter is silent. This is emphasized by the second helicopter that appears at 1:30 — you can clearly hear its engine noise and rotor chop.
I would say the pilot is admirable, far from crashing "in the most idiotic way possible."