Well, they had to get the clicks, I suppose. :-) But, yeah, getting 'overdosed' on weed is a non-existent problem. Medically, you simply cannot harm yourself by overdoing it (to get anything approaching lethal doses you'd have to smoke kilos of the stuff at once, a physical impossibility). And if you overdo it, you simply won't be having a good time, so the natural tendency is to stop well before you get to a bad place.

Becoming paranoid, anxious or having a 'bad high' is mostly a function of your pre-existing emotional state or a function of your surroundings. As the erowid crowd likes to say, "set and setting". Before partaking in *any* psychoactive substances you need to be sure that your set (emotional state) and setting (your surroundings) are conductive to a positive experience. If they're not (you feel bad about something, you're in an unfamiliar or unsafe surroundings) then you risk having an unpleasant experience and should probably lay off the stuff.