If we just take his examples though, then the problem is on its way to being solved. So he puts movies on his queue that he doesn't watch? Great, he should gi

If we just take his examples though, then the problem is on its way to being solved. So he puts movies on his queue that he doesn't watch? Great, he should give them low rankings. If the algorithm is good, that problem is solved. He likes some movies at night, some on the weekends and some with his wife? Well, okay, rate the movies how you thought they were when you saw them. The algorithm will recommend some movies for each situation. Your preferences change over time? Thats a bit harder, but was also out of the scope of the challenge. They were given static data. If you want to account for changes over time, then give the ratings some weighting that decreases over time or only use the last x months of data. But, like you said, he probably doesn't know much about the algorithm.