Movies and Advertising
There is a long history of advertising in movies. This is not the blatant kind of commercial you will see on TV. Movie advertisements are subtle. Every time you see a character in a movie drinking a coke, you can be pretty sure it is an advertisement. Likewise with billboards for various products you see flash on the screen in the middle of a high-speed chase. Movie producers do not want to distract their viewers from the action in a movie. This would only annoy people who have paid a premium ticket price to watch the movie. At the same time, there are also blatant advertisements at the start of every movie you will see at a theater or on DVD. These are the previews. Of course the people who make movies want you to go to more movies, so they show you exciting scenes from movies to pique your interest in their other products.
Movies tend to buy more advertising than they sell. You will often see many advertisements for different movies on TV before a given show is released. A movie is an entertainment product, and as such it is sold with the techniques of advertising. There are many magazines and websites devoted to nothing but movies and the film industry. With billions of dollars of revenue at stake, there is no shortage of hype that goes along with each production.
Celebrities are both advertising for movies, and advertising for themselves. In the entertainment industry, famous stars are advertisements for a given film, and self-promotion machines. If you see a famous actress in a show, this alone might make you want to see the movie. You may also be inclined to purchase fan type material like T-shirts or dolls or books about these people, who are also in themselves products for consumption in the entertainment industry. In many ways a movie is like a long advertisement for a celebrity, in that if they are entertaining, a viewer will be more inclined to see other movies with this same person starring.
I doubt there will ever be TV style commercials in the middle of theater movies. TV commercials are by their very nature an interruption and an aggravation. Aside from short bits shown as part of a scene where some character is watching TV, there are few instances of commercials in film. In a movie you have viewers who have paid a premium price for the pleasure of viewing an uninterrupted show. They will not react kindly and come back to spend more money if they are annoyed by being sold food or cars in the middle of their entertainment. On TV they get away with this kind of annoyance, because there is no other way besides donations or taxes to make television a profitable business. Movies bypass the need for advertising by charging for admission.