Ugh theres not many things I find more annoying than people who talk all through a film. If you want to do that, wait for it to come out on dvd or something and watch at home, why inconvenience everyone else as you want to yap?
I don't think I would have point blank ignored her though, but I would defintiely have said 'oh tell me after the film, I and others are trying to watch it!' or something, THEN ignored her or said again to shut up. Hell, if she kept yapping I might possibly have moved seats away from her so she couldnt talk anymore unless she wanted to talk to herself. I would be, along with annoyed, concerned that those around me (who even if they said nothing will have been pissed off) were thinking I was as much of a twat as she is.
I don't get it at all. I can understand it a bit more with young kids who might be there for the first time or whatever, but adults who do it are just arseholes. Theres no reason to do it, you must know you do it so basically, if you cannot stop yourself doing it, don't go to the fucking cinema at all. Self centred knobs.
Yes, it makes me rage a bit. I didn't see a AIBU as such in your OP, but even though you are wanting friends, I would avoid this woman like the plague. Shes clearly just self centred and..well annoying.