Not to encourage nor discourage any particular activity, just an observation. I've noticed that some video content is leaked online before it's even officially available. I wonder, for instance, how it is that I can find, on a website with a logo that looks like a ship, (not confirming whether I did or didn't actually download, just that it was there), a file ripped from a blu-ray disc several days ago, but I cannot legally buy the blu-ray until this Friday! (in this case, the content is the 2nd installment of a popular teen dystopian fantasy with an Oscar-winning female lead) Pirates in the warehouse? Or in the disc manufacturer? Or in the studio? Who knows! The interwebs never ceases to amaze.
I reckon it's the same as when WZT leaks a new Windows iso before it hits the shelves. Some people get access to the disc before the release date and *cough* share it with someone else. That 2nd party runs the disc files through the conversion process to compress and lower the bitrate of the data and puts it in a multi-channel file such as mkv or mp4 It's really amazing how those folks at YIFY get the quality so high on such small releases though... That's just crazy... Someone at netflix should hire them or something.