Have you seen the Happy Meal toys & some of the boxes lately? With all of the various movie tie-ins and whatnot, it's only a matter of time before Happy Meals are completely subsidized by the toys included.
When my kids were younger, it became a Disney tie-in vehicle. My all time favorite was one happy-meal toy line with each Disney character from an animated movie standing on a rollable (wheeled) video-cassette case for the movie.
I suspect the movie makes money from the toy's vs paying for that advertising. Plenty of kids will beg for a happy meal because they want that cheap plastic, and the parents eat where the kids eat.