Measure Audience Engagement with Internet Video
http://www.visiblemeasures.com/video-engagement/

Visible Measures
2009

Abstract:

A video's Engagement Curve is a visual representation of the audience's cumulative interactions with the video. An Engagement Curve quickly reveals which parts of the video clip the audience finds compelling -- in the example above, viewers are clearly rewinding to re-watch a segment in the middle -- and which parts do not hold the viewers' attenion -- in this case, the end. An Engagement Curve is read from left-to-right, with the left edge representing the beginning of the video and the right edge representing the end of the video. The dashed grey line shows the view-count, while the blue line shows many times that particular segment of the video was watched