What is the algorithm for selecting the best scene of a video?

Question

When we upload a video to Youtube or other video sharing sites, the site automatically selects the best or the most representative scene from the video to show as the icon of the video. How is that done? I want to know which data mining or other algorithms to study to extract the most relevant scene from a video. Any pointers to literature or implementations would be very useful.

Answer 1

I strongly suspect that the "algorithm" is roughly (in pseudo-code):

Random(0, clip.Length)