a private (whatever that means) anonymous filesharing network

Many filesharing apps used the same protocol talking to the same servers. It was just different clients accessing the same data. (All the Gnutella clients talk to the same ``network''. Kazaa is used by many different clients, IIRC, even though they don't come out and say that. Folks used the Napster protocol to set up ``networks'' outside Napster's control.) They mean that Blubster's data is Blubster-specific. You won't find the same stuff on Napster clones or Kazaa or whatever.