It's easy to get distorted views about things like this when you look at the demographic on a website like this. It's easy to form a perception that 'everyone buys them'
I'd say a massive majority of ski movie sales would go to NS.com and TGR members, then the subscribers to Powder and Freeskier mags - outside of that, it would probably be scattered with a few % here and there out of retail stores..
Think about rockclimbing or skydiving movies - similar subcultures to what we have, and i'm sure the figures would be similar (rockclimbing would probably exceed numbers for ski movie sales)
I give so much props out to ski movie filmers because it must take such hard work, most of the year. On top of that you have massive costs which aren't regained until people actually buy the movie (E.g. the Heli cost for the Keystone shoot in Realtime, Accomodation, Transportation etc) - that shit is super expensive.
Sponsors would need to play a massive part in helping with budgeting, but either way I don't think there are too many millionaires in the ski-movie making business - all for the love of the sport. I'd definitely be stoked to do it.
It's for these reasons that things such as posting links for downloads of ski movies on the net is so frowned upon here. The $30 is easily justified.