What is this? Get an App and record him abusing you? Honestly, what?!
This is the way I see it: "I posted a rude comment on a friend's FaceBook Account, and then he pushed me out of a window and killed me."
Thats fucked up.. I see how you were in the wrong in the first place by invading his privacy, but I can also see how you could be paranoid of being hurt by someone who can blow up and threaten to murder you so easily.
You definitely shouldn't go with temporary or drastic solutions ((avoiding him forever (if he really is psycho, then a dangerous grudge could build up until he finally hurts you, himself, or those around him), trying to get him arrested (once again, grudge. when he gets out then that could turn into an entirely new problem, and then your family would be in danger as well, not to mention you could be ruining a normal person's life if he was really okay. if he isn't jailed it might make it worse), deferring to the staff (as the others have said, they probably couldn't do anything aside from aggravate his condition, if he has one.) )) as those could easily have horrid consequences and might only alienate him further. I think you should try talking to him one-on-one after letting him cool off for a week. Just try to talk about how much he scared you, why you're sorry, and ask him if he's been feeling alright lately. If he chills out, and lets you know he was just having a bad day, or similar, then thats a load off of your mind. If he flips again, or threatens you once more, then you might want to be worried, and you can definitely go and get some help in good conscience.