Go to http:youtube/trends and all you’ll find is a blog. You need to go to the dashboard, here: http://www.youtube.com/trendsdashboard to actually find YouTube Trends as see what it does. God only knows why they didn’t mention any of that in the video.
What does it does? It allows you to search for most viewed and most popular videos, limiting your search by age range, sex and geographic location.
It could be quite useful to web series producers.