The riders get paid by thier sponsors. The movie companies don't pay the athletes to be in the movies. Warren Miller pays people that are not under contract, they pay $50.00 per day for food. I had a friend make around $50.00 per day from WM to make powder turns.
Sometimes the film company will help out with some travel cash for part of a trip, or they will talk to the sponsor to help out an athlete, especially if they are new to the scene. Thats only if you are worth it to the movie company to be shot in the first place. Or the movie company will get the athlete a sponsor that sponsors thier movie.
Basically an athlete should have a travel budget to go on trips, if they don't then they are paying out of thier own pockets. Thats the case most of the time.
For athletes to get royalties from a movie they need to have a contract with the movie company to get that. Some may get a royalty, but maybe just the rider owned and operated ones.
Sometimes a sponsor will sponsor a trip with thier athtletes and have a filmerr from a company come along. That is how it is done in Warren Miller most of time.
Companies that Sponsor a film are not paying by the minute. They are paying for exposure of thier products. If they pay a certain amount they get a logo on the box, and at the bigging of the movie and those chessey product shots you see in an athletes segment.
Sometimes athletes have a film incentive built into thier contracts where they get money for a segment that is so long, and then more money for a segment that is longer.
All in all it is up to the athlete or thier agent to geth them these types of deals.