If you use the search feature above right for<preview and video> you will find something to help you.
The particular thread might help -- or confuse: as it is not VERY recent and refers to a Beta version
http://www.gnutellaforums.com/showth...view+and+video
I think LW only previews mp3, but my video experience is limited hence I'm pushing you off to other threads.
All I do know is that a LOT of video files ou there are misrepresented, I'm afraid.
Let us know how you get on.