Have a look at this thread to get an idea where these types of files come from:
Quality of Content on the Network (click on link) Personally I always filter .jpg & .wmv out using keywd filters. But if you're searching for jpg & wmv files, then obviously you can't do that. For wmv files, they should be above 10 MB in size! Of course depending upon what type of wmv files you'e after. For popular movies I's suggest 100+ MB. Be suspicious of any that have particularly long names.