I'd suggest this is a deliberate leak by Fox of a big budget film which the company had high hopes for, but which has completely failed to generate any hype or buzz in the face of all the other blockbusters which are due out in the next few weeks.
Release a good quality copy sans special effects via the back door, people who may be interested in the film or who didn't know about it, may see the leak, and if they like it, will hopefully pay to see the finished version.
DVD copies of the leak will be given to family members and frienRAB. . .viola, free advertising for a film which no one would've paid to see if they'd not seen the pirate.
Let's not be so daft as to think that someone at a special effects company leaked this.