MovieLens 20M Dataset
Stable benchmark dataset. 20 million ratings and 465,000 tag applications applied to 27,000 movies by 138,000 users. Includes tag genome data with 12 million relevance scores across 1,100 tags. Released 4/2015; updated 10/2016 to update links.csv and add tag genome data.
Also see the MovieLens 20M YouTube Trailers Dataset for links between MovieLens movies and movie trailers hosted on YouTube.