Be careful, though! A couple on Chaturbate just got busted doing one. It happens. And if you get arrested (depending on where you live, the librarians and cops might be more douchebaggy about making an example of you than in other jurisdictions), it makes the news with your real name.
And as a former librarian, I can tell you the security cameras are there because you wouldn't believe the crap people do in libraries--public sex, shooting up, taking a dump in a book, etc.