If you're in charge of figuring out what's popular in a given market, regardless of what topic you're dealing with, you're likely to go to a place where you know you'll easily accomplish that goal. Take for example the latest video games - if you own a store need to gauge how many copies of a particular title you should be bringing in, the amount of hype you see at a specialized gaming site can help with that. Likewise, the same sort of sleuthing could be done by content delivery services to determine what they should seek out.
Going to technically illegal sources to determine something for a legal business might seem a bit unusual, but it's rather smart. Netflix considers those who pirate content to be their customer with the biggest potential - so why not make sure the content they want is on your legal service? It seems like a win-win for Netflix, and the content companies it represents.
This is especially true in markets that Netflix isn't too familiar with. Recently, it launched its service in the Netherlands, and to help beef its offerings up, it once again headed on over to select pirate sites in order to determine what's popular. TorrentFreak, the website that revealed this news, regularly publishes "top lists" for the most downloaded TV shows and movies - and who knows, maybe companies like Netflix actually take them into consideration as well.
Regardless - one thing from this becomes super-clear: When it comes to business, it pays to think outside the box, and sometimes pursue avenues that might seem a little ridiculous at first.