I can tell you 1st hand that they know exactly where you are. Back in November, I hooked my brother-in-law up with all of the multicast addresses and showed him how to view all of the channels on his PC. For Christmas, he asked for a video card with TV out so that he can watch them on his TV. Two weeks ago he was called by Sasktel for viewing channels that he did not subscribe too.
I myself had Sasktel up until last week and I can honestly say that I had been known for making the odd transport stream capture, but more often than not I used it to watch channels that I subscribed to in the kitchen on my laptop where there isn't a TV. Especially in the morning so that my kids could watch TV while they ate breakfast.
If SaskTel is concerned about people tapping into channels that they do not subscribe to, then perhaps they should do what any responsible cable/sat company would do and encrypt their channels. Right now any 12 yr old with an Internet connection could be capturing Playboy/Hustler and making DVD's for all of his friends.
Just to add, is it signal theft if you use the technology to view channels that you subscribe to on your PC? You are still limited to 2 simultaneous connections whether it be PC or STB.