He took off without closing the doors or waiting for the people standing around to move aside, or turning the helipilots on. Ground resonance could be a reason for him doing that. Maybe next time he'll leave the hp's on, and maybe check up slightly on the collective instead of keeping it all the way at the bottom.
412 isn't that bad without the hp's turned on, no worse than a 76. You can usually hover both without scaring anyone and reach down and turn them on. Helps if you've done it once or twice before.