There is a Gallery
photo gallery hack/add-on that automagically extracts a given video frame and generates the corresponding thumbnail. I dunno how much work it'd be to incorporate that into vB adv gallery ??
Uses this library:
is an extension for PHP that adds an easy to use, object-oriented API for accessing and retrieving information from video and audio files. It has methods for returning frames from movie files as images that can be manipulated using PHP's image functions. This works well for automatically creating thumbnail images from movies.
ffmpeg-php is also useful for reporting the duration and bitrate of audio files (mp3, wma...). ffmpeg-php can access many of the video formats supported by ffmpeg (mov, avi, mpg, wmv...)