You just have to be connected when you start to watch the FIRST movie on a particular machine. After that, the rights are apparently established, and you can play that movie, or others you've downloaded, at another time when you aren't connected.
I do that, with the laptop SVID and stereo outs plugged into my main tv, and I couldn't tell it wasn't a rental from Blockbuster - except it "returns" itself, and I get no late fees.
