I've manually sent hundreds per year myself, which is getting to be a nuisance, like whack-a-mole. Why should people buy your stuff when they can google it and see a ton of instant download links from a lot of filesharing sites? It's become a big issue. It's killing adult sites, and they're a precursor for trends in information marketing; eg for sales for those of us in non-adult niche traditional niches as well.
One colleague I know said he hires a part time paralegal (he has a big online business that sells dvd systems for his niche, which are pirated a lot).
Every week, I set aside an hour or so to search out (or respond to automated google alerts searches), to send out dmca@(sites) notices to takedown copies of my dvds and premium online videos.
It's a waste of time, but absolutely necessary to make it hard to find my content. So many people in my industry (trading) seem to stick their heads in the sand when I ask them what they do, then complain about low sales.
And NO it's not a valid argument, imo, that "well the people who downloaded from filesharing sites wouldn't have bought from you anyways"... while it's true that there are a lot of people who wouldn't pay, there's ALSO a lot of "people who would've paid, but after googling and searching the pirate info-forums/blogs, just downloaded it for free anyways". That's the issue.
What about you? Google your product you've created with the name of any of the filesharing sites and you'll likely see some links. It would be nice to get this taken care of /outsource it. What I'm thinking I'll do in 2012 is outsource that to someplace or hire a temp service to do this, as an hour a week is a lot of time to me, to spend on this bs. Existing services are far too expensive, from what I've seen, when googling 'dmca takedown notices'. Any ideas?