The impact of film piracy increases the longer the time allowed between US premiere and opening elsewhere

"[A] new study reveals that movie industry itself has the key to decreasing piracy, without passing any news laws.
In a paper titled ‘Reel Piracy: The Effect of Online Film Piracy on International Box Office Sales’ researchers from the University of Minnesota and Wellesley College examine the link between BitTorrent piracy and box office returns. As hypothesized, they find that international movie piracy losses are directly linked to the delay between US and foreign premieres.
In other words, the longer it takes before a movie is released internationally, the more box office revenues are impacted through piracy.
“We find that longer release windows are associated with decreased box office returns, even after controlling for film and country fixed effects. This relationship is much stronger in contexts where piracy is more prevalent: after BitTorrent’s adoption and in heavily pirated genres,” they write.
“Our findings indicate that, as a lower bound, international box office returns in our sample were at least 7% lower than they would have been in the absence of pre-release piracy.”"
Source:  TorrentFreak, 10th February 2012