I know in basketball if you are a high school player and make one of those half court shots or whatever, if you accept a prize, such as a car, you could lose your NCAA eligibility. That came up a few years back. If memory serves, the kid kept the car or whatever the prize was and forego a chance to play in college.

Again if memory serves, the ruling was something to the effect that if you gain something of monetary value based upon your skill in that sport, it would make you a "pro".

That being said, guessing there are exceptions for "odd" cases, such as being in a movie.