The theaters are not really on board other than participating. The MoviePass guys generally don't get discounts on tickets because the studios usually define the ticket price and the theaters have to negotiate with the studios to set the prices - so they are pretty strict about ticket prices.
However, the theaters get bodies into their empty theaters and since most of their revenue is from sales inside the theater for food, drinks, trinkets, and memorabilia, they really want to get more bodies in the theaters if they can. So, Movie Pass, which does not yet have a profitable model, thinks that once they get enough steady subscribers they can find a way to monetize their service through selling advertising to theaters and studios as well as retailers who just want more eyes on their brands and products. This is getting a ton of attention in the entertainment financial world because the thought up until this venture was that people were truly losing interest in going to theaters. This might be a new model which turns around that trend.
