I was referring to both cinema and watching sports actually. I know watching sports includes a lot of drama, but then there are also films with drama, obviously.
The bolded part: how can you be so sure? Just because you don't agree and couldn't feel that way, no-one can?
To go into this a bit further: lots of people will say that sports are anti-intellectual and pointless, and will never get why anyone would care about them. I suppose you'd reject that as elitist bullshit, and you'd be right. But it's the same in this case. Personally, I'm a pretty reserved and introverted person, I won't be getting openly or very emotional about much, and you will never hear me shouting at a film at home. But I wouldn't shout at sports on tv either (apart from the occasional 'Yes!' or "No!'). When I'm in a stadium, however, I go along with the crowd and cheer and jeer and whatever. It's probably the same with these people: if one of these shouters were alone in a cinema full of quiet people, they wouldn't be cheering cause they wouldn't get into that mood on their own. In a theatre full of people working each other up, however, it's a different story. I also watched a popcorn movie at a big outdoors music festival once, and everyone was shouting and cheering and everything also. And no, that wasn't a great emotional masterpiece either.
Also, obviously Spiderman wins. Duh. I don't suppose that's what they're cheering about though. It's how the filmmakers make it happen. In football, it's cool if your team crushes the opponent and wins 5-0, cause it's usually unexpected (except if you're City these days). In film, if Spiderman were defeating his enemies the same way, it would be super boring and no-one would be cheering. But stuff like Captain America picking up Thor's hammer in the final showdown with Thanos - that's just super cool if you're a big Marvel fan. (I also thought it was cool, but I didn't cheer. I probably would've if I had been in the room with these people though. Why not get along with the fun emotions?)
And anyway, films are doctored to affect your emotions. The scene where the guy hangs himself in The Shawnshank Redemption is immensely sad, as is the pier scene in The Remains of the Day, or most of The Barbarian Invasions. The ending of Fight Club every time makes me feel all confused and worried; and the ending to the Usual Suspects is very cool. None of that is fist-pumping stuff, of course, but then they are all much more cerebral films. It's not quite the right frame of reference - it's like wondering why people aren't experiencing Radiohead's Street Spirit and Green Day's Basket Case the same way.
Are you suggesting that this wouldn't have happened if people had been enjoying Spiderman in silence?