You are jumping to speculations and ignoring the facts in front of you:
- OpSec Online Antipiracy detected the download, not Xfinity
- BitTorrent clients have to know who is serving what content (that's the whole point of P2P networks)
So, by checking out the company, they say:
OpSec® PeerScan enables you to protect your content against Peer-to-Peer (P2P) piracy abuse. Its unique intelligence enables you to see the number of peers connecting to a swarm, their geo-location, title, asset quality, and language ...
and then
Industry-leading BitTorrent Level 1 public trackers and Distributed Hash Table (DHT) client designed from the ground up to provide excellent scheduling and data capture capabilities.
and
Powered by OpSec® PeerScan, OpSec® Acuity Pro systematically monitors an index of music, film, and television titles worldwide to provide visibility into piracy consumption across different markets and media on file-sharing networks. This data helps you gain a deeper understanding of when, where, and how copyrighted content is being used
So, it's all quite simple: OpSec Security simply watches active BitTorrent traffic, as anyone can do from their own BitTorrent clients, and reports to copyright holders.
