What's the difference between a single image and a video? Well, video is a timed medium, otherwise called a time-continuous or time-synchronized medium. It's impossible to take in at a glance, and in order to appreciate it, or derive any benefit from it at all, you have to devote time to watching it.
Watching would be more efficient if we didn't need to watch from end to end, but rather had some sort of a road map for the video: an intelligent players that would give us signposts, provide us with an indication of where the video could be most interesting.
I was invited to give a position statement at a session on search at ICTDelta 2010, a larger IT event in the Netherlands. I took the position that we need to have intelligent multimedia players that give us clues as to where the video is the most interesting as my position. The position statement was in Dutch, but I made an English version in the form of a YouTube video.