See these:
Fake movies & why & also
Quality of Content on the Network
And also see this about posting about copyrights:
http://www.gnutellaforums.com/announ...?s=&forumid=29
The size is a telling factor. Also unless you are really after wmv files stay away from them. Instead try mpg/mpeg, avi, divx, ...
You can use your Keyword Filters to filter out certain types or names of files. For example I filter out jpg, wmv & exe. But these can be added or removed anytime.