Vidmeter tracks the popular videos across the web, giving you a hourly updated list that reflects what’s hot across 11 sites. You can get a widget that displays the hot stuff on your site as well.
Now what would really help me is if I can take this site and its monitoring and use it for videos that I want to track – let me put in a list of video URLS and track views and comments for me. Even if it can’t do that, it does give me some benchmarks of ‘successful videos’ so I can use for clients.