Did a little digging and I am seeing something that says that it does need to "stream" down to your device, but it sounds more like a download than a true stream, so that is good. Just plan ahead so that you have the bandwidth/time to download it before you need it. Also, there seems to be a limit on most/all of the movies that they can be "streamed" 3 times.
Who knows. Maybe those folks over at Blu-Ray.com are just crazy.