Borrowing things implies consent. He asks, "hey, can I borrow this". When he just takes things with out consent, I'm pretty sure that is the definition of stealing. Yes you should consider them a thief. Yes you should change your locks. This person sounds like they have no respect or care for anyone. Stealing from friends is damn low. Video taping people without consent is potentially a criminal act. Stealing condoms is funny. You can get them free at the doctors office or clinic. Stealing medication is a major problem. I personally can't stand pill-heads. Even if they ain't stealing my meds, they're real annoying. And food... I'd give food to a stranger if they were hungry, but steal it and I'll let you starve.
