> Wasabi also noted that the way the remote URLs are configured, there are only 65,535 combinations to try, "which a computer can run through pretty quick.") - From the ars article

It's a bit confusing, but I think they what they are implying is that there is a total of 65,535 possible keys. Devices may be assigned one of those randomly. The URL must send the key and some sort of device ID. It's possible that if you know the device ID, it would only take 65,535 attempts to gain access to the stream.