I've never cried while watching one, but I have felt strong emotions caused by films.
I can understand not being able to relate to those who cry, but I can't figure out when people call them pathetic.
I remember it was right after 9/11 and our school had an assembly where we went outside and had a moment of silence crowded around the flagpole with the stars and stripes at half-mast. Some girls started crying and people were saying they were being ridiculous, which I was kinda just surprised at them being so insensitive.
Some people are very empathetic and even if they've never actually been in the same situation, they can relate to what they see in the movie and this can make them feel as though they are feeling the same as the people in the film would.