I don't really know if this is good or not but thi sis the only thing I have ever used.
It can automaticly create thumbnails from almost any movie and save them, can also select which frame and all that.
I think its actualy for managing movies and mp3s and shit like that on your own comp but it does the job well.
http://www.topshareware.com/MagicMed...nload-2300.htm