Here's a citation arguing that pirated content has no impact on DVD sales "With respect to the impact of piracy on sales, we use the television broadcast as an exogenous demand shock and find that the availability of pirated content at the time of broadcast has no effect on post broadcast DVD sales gains.":

http://www.heinz.cmu.edu/~rtelang/SmithTelang.pdf

These guys say that pre-release pirated movies result in a 15% decline in box office revenue "We estimate that the net effect of pre-release piracy is approximately a 15% reduction in box office sales.":

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1782924

That's what I was going to ask. Many papers I find sifting through looking for evidence supporting this, actually refute this claim. So I'm curious what sources this poster is using.