Video Contact Sheet *NIX (vcs for short) is a script that creates a contact sheet (preview) from videos by taking still captures distributed over the length of the video. The output image contains useful information on the video such as codecs, file size, screen size, frame rate, and length. It requires mplayer, ImageMagick (convert and montage), bc, and ffmpeg.

check it out :
http://freshmeat.net/projects/video-contact-sheet