You can write a stream to file with maybe 2 commands, and try to decode it later.
If the DRM on the stream is broken, you can save the stream to file and decode it later. If the DRM on the stream is safe, then it should be equally safe between the stream and saving the file to disk.
I fail to see how letting you save encrypted stuff to local disc has anything to do with breaking the DRM.
Also, the first thought people have when given a new service for free is "how can I use this to pirate movies". This is why we can't have nice stuff.....