Not only can they predict it, but I imagine to a large extent they control what people watch. Our usage often involves browsing the recommendations on the home page and picking something.
I wonder when (or if) the availability of content in a cache close to the viewer will play a role in the home page content? Obviously it already works in the other direction (cache what we think they'll want to watch), but do they penalize the ranking of a title (or category) because it hasn't been cached?
It'd be a useful feature for Netflix because they could cut down their bandwidth costs. It could even be useful for some users: those who could watch a movie at full quality from a cache but their ISP can't deliver a full quality non-cached title.