YouTube takes the business of tailoring your search results very seriously. So seriously, in fact, that it has over 1 million lines of code in place to pair up the videos on its servers to you and your preferences.
This video interview with Christos Goodrow from YouTube talks around-without describing in precise detail-YouTube's search algorithms. He explains why videos are no longer ranked by view count-and gives away just a little bit of detail about what they're using instead. [Computerphile]