The research investigated box office sales over a five-year period covering 1,344 released movies in 49 countries. According to their findings, overall movie revenues decreased following the shutdown, but smaller and major movie releases were affected in different ways:
"[…] the shutdown had a negative, yet in some cases insignificant effect on box office revenues." Not all movies were negatively affected: "For blockbusters (shown on more than 500 screens) the sign is positive (and significant, depending on the specification)."
The finding that blockbusters were positively affected by the Megaupload shutdown opens the door for a wide range of speculation, without any clear-cut explanation. However, the researchers offered this version:
"Our counterintuitive finding may suggest support for the theoretical perspective of (social) network effects where file-sharing acts as a mechanism to spread information about a good from consumers with zero or low willingness to pay to users with high willingness to pay. The information-spreading effect of illegal downloads seems to be especially important for movies with smaller audiences."
If that is the case, then we could conclude that the word-of-mouth engine promoted by Megaupload especially benefited smaller productions that don't have access to the marketing resources of larger movies.