From the post:
It wasn't just that the improvement was marginal, but that Netflix's business had shifted and the way customers used its product, and the kinds of recommendations the company had done, had shifted too. Suddenly, the prize winning solution just wasn't that useful -- in part because many people were streaming videos rather than renting DVDs -- and it turns out that the recommendation for streaming videos is different than for rental viewing a few days later.(Via Marginal Revolution.)
