You can filter them. In LW go to Tools>Options>+Filters>Keywords> then type the file extension in the box click add.
That will filter out all those file types (like asx or mov ect). So if you like to d/l some of those file types you would have to remove the filter to see them.
Also the newest beta version has a spam filter in it. I haven't tried it but if your interested see this thread:
http://www.gnutellaforums.com/showth...threadid=49911