talkmagic.co.uk

There are two points here and neither are worth you getting hung up about.

The first is the illegal download but if they had purchased the discs legally and then performed the routine in the way that they did, would it have made it OK?

You can't stop people copying you and it shows a lack of originality on their part. Just remind people where they saw it first and then come up with something new. This time, don't spill the beans on where it's from.

I always refer people to a book rather than a DVD remembering that old saying of "if you want to keep a magical secret then publish it in a book". These people won't be bothered to read.

One thing you could've done was given them the name of another magician. I once made the mistake of telling a friend interested in magic where I learned a particular trick, and he went and torrented the enitre DVD collection it came from. So to avoid that I usually give him the wrong name of either the effect or its creator just to stop him from doing that again.