In addition to an older tactic of offering bogus downloads that never complete, HBO is now obstructing the downloads offered by other people. BitTorrent downloads are peer-to-peer, but the peers are introduced to each other by a tracker ("you're looking for Rome Season 1 Episode 2, talk to 127.0.0.1"). HBO runs peers that tell the tracker they have all the chunks of the show, but then send garbage data when a downloader requests a chunk. The downloading client can detect that it's garbage and will try another peer for the chunk, but the end result is that it takes much much longer to download shows.
email Curtis