I have added a few URLs to the blacklist but I'm not sure this will do much to combat the spammers. Besides, there's hundreds of those sites out there, they'll probably just use different domains. With the popularity of sites like YouTube, Vimeo, Metacafe et al. always rising, video conversion software is only going to get more popular too since people still own shitty hardware that can't play back widely used standards these days.
Not really sure what else we can do at the moment.
And as you may have noticed I unfortunately don't have much time for this or any other of my sites right now.