This is a problem with online videos and web performance measurement: we know if a video is "clicked" or not, but nothing more. Youtube wants to remedy this problem with Youtube insights, the Google Analytics of online video.
It's still pretty basic I think. I would have liked more advanced features such as streametrics.tv, although some believe otherwise.
Basically, what Youtube Insights adds is the timeline of the views of a video and also the geographical origin of the visitors:
My Account > Videos > About this video (context button to each video)
What would really interest me? The completion rate of videos as well as the average view time per visitor. The recurrence rate of a visitor too.
I still wanted to highlight an interesting interface element, the browser allowing you to see the views over time:
Can't wait for the version with more options!
The official announcement by Youtube !