observation over a film watched

Well the last time I went to the actual cinema was to see Shindler's List which as you probably know is set in the holocaust. The guy sitting next to me annoyed me so much as every time something awful happened on screen, such as the Commandant randomly shooting prisoners from his balcony, he burst out laughing. It was a completely inappropriate response and my luck to be sitting right by the only person there who was laughing like a maniac at a very moving film. It's put me off the cinema ever since and now I prefer to watch a movie at home.

Ignore them. I've tried everything short of physically hurting somebody: sarcasm, telling the person to keep quiet in a nice and a not so nice way, glaring at the person if he/she's beside/behind me, etc., etc. I usually end up walking out of the movie house because they just won't shut up.