I'm guilty of doing it myself...taking off my seat belt after the flight attendant walks away. I've done it, but never will again. When they tell you to strap in it's so that THIS doesn't happen to you. Anything that isn't locked down can be whipped quickly in any direction, no matter what it weighs or what it is. These people were terrified I'm sure. At least 10 injured. This was a flight from Serbia to Switzerland.