A Hypothetical Question to the Boing Boing Community: the Filmmaker and the Bittorrented Screener

I attended a private screening of a yet-unreleased new movie today, hosted by the director of that movie. At the end of the screening, the filmmaker shared with me that a rough cut of this film had been leaked to BitTorrent, with the screener blurb marking ("PROPERTY OF #### FILMS, DUPLICATION PROHIBITED" or something) clearly placed on every frame. The filmmaker was upset about this and asked what they ought to do, if anything, to try and stem its spread, or deal with whatever unknown damage the leak might cause. Here's the interesting part: their concern mostly stemmed from the fact that this was not the final cut or mix of the film, and the filmmaker didn't consider it a finished work. For them, it wasn't a perfect enough, complete enough, final enough product. And I'm confident this wasn't a faked "leak" designed to drum up publicity. I told them I'd ask someone with expertise, but then thought it might be more interesting to ask all of you. If you were advising this filmmaker, and you knew they wanted to do the right thing by the internet community *and* by the film and all the people who worked on it -- what would you do or not do, say or not say? By the way, the film was amazing.