Mm, I love the smell of data in the work day. Introduced in March 2008, YouTube Insight data and stats on video usage. In May of that year, they added demographic data.
YouTube's done a decent job of winning over content creators and rights holders, and its Content ID system, which lets them identify and profit from user-uploaded clips, has been a big part of that. Content ID may become an even more popular feature, too, now that a quirk has been ironed out.
YouTube's Content ID system appears to have caught on in a big way. This afternoon, a senior product manager stated that over 1,000 content owners now make use of it, and that they've provided more than 1 million reference files containing about 100,000 hours' worth of material.