I find this to be true in my own personal experience. This is just an anecdote but if a movie looks really good, I’ll go see it because I want the full experience (i.e. anything by Guillermo Del Toro). When I have random time to kill, I pirate movies I’m not sure are worth $11 for a one-time viewing. If I couldn’t pirate those movies, I still wouldn’t go see them. So movie theaters are not loosing my business because of piracy because I basically only pirate movies I wouldn’t have seen. Same concept applies to DVDs. I buy movies I really want because I want the director commentary (again, especially anything by Guillermo Del Toro.)
An interesting side effect I’ve noticed is sometimes a movie I pirate will surprise me so I’ll run out and see it in theaters for the full experience or go buy it on DVD so I can nerd out on the special features. So in this case, piracy actually lead to a sale.
Piracy doesn’t reduce the amount of money I spend on movies because I wouldn’t have bought the movies I pirate anyway. But on rare occasion, I will go out and buy a movie I wouldn’t have purchased otherwise because I pirated it and liked it, thereby increasing sales.
The same concept applies to music. All of the physical and digital copies of music I’ve purchased over the last 5 years is a direct result of discovering those songs on youtube.
Anyway, I don’t know what the point of all that was. I just felt like sharing.