I downloaded this movie but Im not really worried I own the movie now and long ago deleted the digital copy. They will never be able to tell if I have the pirated version or not, unless they supeona my HD which they wont.
They can't legally check your hard drive.
What they do do is figure out where the traffic is going, find your IP address, then contact your ISP who owns the IP address... Then you can figure where it goes from there. They just know that you uploaded the file, they don't know if you even still have it on your HDD.
Most of the time they tell the ISP, "Take action or we will sue you for facilitating illegal file sharing". The ISP usually disables the customers internet connection, then you gotta call and they tell you that illegal file sharing was going on, then you say pretty much anything and they say, "Oh, well, don't do that again. We're reinstating your service. If you do it again we
might terminate your service"
Easiest to just say, "Oh, I don't know anything about file sharing. I do have an open wireless connection, could that be it?" Then they will just say, "Yes we recommend that you set up a secure wireless internet access-point"
I've heard of people getting their stuff shut down like 4 times, I've never heard of actual termination of service. The ISP's want you to pay them for internet, but they don't want to get sued either. So they take minimal 'action' and try to stay out of the heat.