I mock movies that I like. I effing love Lord of the Rings I've got an entire repertoire of snarky comments for whenever I watch it. I too, hate obnoxious people who talk loudly all through movies. That's why I do so quietly, in whispers to only the people next to me. And I generally don't do it in really crowded theatres either, because yes, I don't want to irritate other people. But interacting with the movie is part of the fun for me, and part of the draw of going to see a movie. I don't want to go sit in a theatre in silence for three hours passively accepting whatever James Cameron chooses to put in front of my eyeballs.

It's rude to talk during a live performance because it distracts the actors. But it's not rude to laugh, or be otherwise actively involved in the show. The role of an audience in a movie and during a play is totally different. Actors on a stage feed off the energy of a live audience - when the audience is inattentive they can tell. It's totally different with a movie. The movie can't tell whether you like it or not. I'm not hurting it's feelings by making fun of it. I don't think a movie is some kind of sacred object that must be respected because of all the hard work put into it. Whether the scriptwriters of Avatar put in any hard work or not is up for debate anyway. God knows I already paid through the nose to go see the damn thing anyway. They've got my money, I don't know if they need my undying sacred respect as well.

It's not like when I go to a movie I sit around chatting about boys or clothes or something. I think about the movie, I talk about the movie. I interact with the movie. It's part of my movie-going experience and what makes it enjoyable to me. I liked Avatar, and I had a good time going to see it. I try not to piss other people in the process, but whatever. You can't please everyone.