The Canadian Film Centre has a collection of Interactive Projects that are impressive examples of what you can do with digital video online. For example, Meanwhile, by David Clark, Jeff Howard (a graduate of Multimedia at Mac), Chris Mendis, and Shelly Simmons, uses a simple interface so you can navigate what happened before or during or after a clip you have seen. You can follow individual trajectories or leap across.
I wonder if one could hack a mashup that lets you do this with YouTube clips … using found digital video.