I always find it a bit odd to hear news media talk about "algorithms" used by Facebook/YouTube/etc. Having worked in machine learning, my experience is that it's less about algorithms and more about massive amounts of data and very simple matrix math.
One of the most famous papers on this is Banko Brill 2001 (http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.19.8013), which basically shows that at a certain point the algorithms don't matter, and if you just throw more data at the problem you get better results.