I believe that the Netflix Prize was fundamentally flawed. They have access to much better information than user rankings, especially for the online service, things like "started but not finished" or "watched all of it the day it came out" and "watched more than once".

That's much more honest feedback than user's star rankings, which can be skewed by a lot of factors: users failing to rate things, rating based on what they feel they should like rather than what they actually enjoy, the psychological anchor of the suggested ranking. It's not surprising that their existing work got most of the value out of that data.

They have much better data now, and I'm sure they're not letting anybody get so much as a glimpse.