Try some of the tips here http://www.gnutellaforums.com/limewi...ind-music.html
which also applies to video. The Keyword filter can work well also if used carefully.
Filtering out .mov files can help remove a % of video spam also.
LW 5 had a size filter which was useful.
If all you are getting is spam, then you can do the ultrapeer removal technique via the Connections window. ie: remove the longest connected one, let FW settle for a few mins, then try searching again. Repeat after 10 -15 minutes or so.