People eating when not hungry during a movie is not a new thing. In fact, I talked about this in the Things You Hate That Everyone Loves thread.
I don’t know whether it’s the association between the movie and eating, or the anticipation of the experience, but it is an external cue, so I agree with the article.
If they’d have sealed the bags of popcorn, they’d have observed that most moviegoers open bags at a set point. Next time you’re at a movie, if you listen carefully, there’ll be a wave of bag opening when the rating screen appears. People rarely eat during trailers unless it’s from an open container.
Also, if you deliberately cough during a movie you’ll hear other people ‘cough back’ in a ‘call and response’ situation- they didn’t ‘need’ to cough, but did anyway.