Can you explain how Public Key Encryption would be related? I was thinking more in terms of a torrent client corrupting a predictable last bit of each saved file (which could cause tons serious corruption issues in itself for non-media files). This appears to only be feasible if each user had their own private key that could be used to compute where the corrupted bit is added to media files.

If you are using a torrent application, it is safe to say that either you or your actual torrent application can connect to the internet and create a key... If you chose to opt out than that is fine, if you choose to opt in you get what was discussed previously.

Not sure why you would go the route of having it predictable?