A production company will, as far as I'm aware, set up a P2P program and download like anyone else. When they get a certain percentage from an IP that makes it identifiable as theirs, then they send out a notice. They can't go by the filename only, but at the same time, they don't need to download the entire file to know that they are downloading their show/movie/song/whatever.
Other options to the safepeer plug in would be Peer Guardian and Blocklist Manager. Peer Guardian does the blocking, Blocklist Manager provides a list of suspect IP ranges.
I think it is possible to use a proxy-like system, such as TOR, but that seems like it would be so slow as to be unusable.
Usenet newsgroups are the ultimate solution, as it is a direct download and you upload nothing, however this has become a subscription service. It once was a regular part of the internet like email and the web, but the bandwidth kept creeping up to the point that ISPs shifted to providing a subscription to a third party newsgroup server and then to eliminating it entirely.
I'd also extend that all the big movie and music producers are very aggressive, as opposed to small/independent labels and, say, game companies (EA excluded).