But if you're providing ancillary services like getting the info to someone in another medium, then it makes sense that you could sell the medium. Kill some lights on the marquee already. That's what potlatch is about. Generosity should inspire generosity not the demand to exploit what you got for free. You'd probably sell more popcorn that evening anyway, if you're worried about it.
Gift culture is about competitive gestures of expenditure.
You're not being foiled in your efforts at generosity, you just don't have the imagination to build on this gesture of generosity in a non-destructive way. Maybe you can't afford that kind of generosity. I couldn't myself. Try to organize putting up a mirror site or something. Almost anyone likely to hear about the stuff that you could reach on the net to sell it to them probably has the bandwidth to download it at their local library.