Recently I discovered some of my magical offerings for download on a magic torrent site (No I won't give you the link). Believe it or not I am actually glad about this. Hell, I might very well be the only magician in the world who is. Crazy you say? Probably. Eating tacos right now? Definitely!
If you got to the big green bean you can find a lot of people in the ethics section bitching an orange streak about how they have been ripped off and pirates are the scourge of the this that or the other. Regardless of where you sit on the subject matter, one thing is for sure, those people are greedy.
If you sell to Murphys Magic then you have made a pretty good penny already off their initial order. (If it's a popular product you have no worries) If it's a download you are of course subject to overnight uploading, but the people who download it are unlikely to buy it anyway or even have the money to do so.
The way I look at it is thus: I would rather have people know my name and like my product to possibly buy future releases. If they like you and what you do they will show it to others and tell them about you. If you are just going to be captain bitchy-pants they will steal from you out of spite.
So be happy they found your items to have the value enough to steal. Then you can release something that ISN'T a damn DVD that they will be forced to buy.