nope the talkback just sent a message to nthell to add the cost of the movie t the bill. The signal was always being sent when you decided to watch the movie the box decrypted it. You could have watched any film without being connected to the phoneline but when the box was next plugged in your billing info would have been updated.
VOD hence Video on Demand requires a talkback in order for the signal to be streamed to you.
Have a look at this post I made in the dreambox section.
It IS possible to watch some VOD/Teleport material, but its no way near as good as what you think - and you are probably best to go rent and copy some dvds