Though this EXTREMELY LOUD video is entitled 'how they watch movies in India,' sweeping generalizations are rarely accurate.
Still, it seems hollering at the screen and showering it with flowers is a fairly common practice in India. And one Redditor notes that it's typical for fans of the film's lead actor to buy out the theater on opening night and go nuts.
As they also point out, the film above appears to be the Tamil gangster-thriller Billa II, which one reviewers called "an underwhelming film experience." If that's true, then I can only imagine the bedlam that went on during screenings of the original.