its just business man. no one is forcing these companies to put their videos on iTunes. In the end I would argue the ski movie companies will make more money because a) its more accessible to more people b) people who may have never seen/known about these niche ski movies might see it on iTunes.
Personally I would never have bought Art of Flight, but since I was bored and on my computer, I grabbed it for 9.99. Even if Apple is taking 50%, they just made 5 bucks they normally would not have.
Anyways, I see what your saying, but I think the big picture is that it's a good thing for the movie companies.