Those T1 sources that litter with spam use dynamic ip's so if you block them one day, the next they'll have a different ip address & some unlucky sucker has adopted that ip address that's blocked! Keep that in mind. Why not just filter out wmv until you need it or ignore those under a certain size. Go LW menu Tools>Options>Filters>Keyword & type in wmv & press the Add button & then the Apply button. Filters can be added or removed anytime so long as you press the Apply button.
Worth a read if you don't like reading:
Quality of Content on the Network and
Fake movies & why and
wmv rubbish and
A Curious Thing Happened... and
XXAA is watching, SPAMing the network, proof and
That's All Folks for now but there's plenty of similar threads if you wish to search for them.