As far as I can tell from the api and the documentation, there isn't a way to watch dvr-ed content unless the live stream is active.
That's a bit like not being to watch old hockey games unless a live one is playing. Yes, that does not make sense.
I implore you to allow access to dvr content without coupling it to live streams. It simply does not make sense any other way.
Currently my extremely tortured method of gaining access to the dvrstream is to quickly turn on and off the stream and then attempt access to the dvr recorder.
The reason it works is that I hang my httpprovider in an infinite node traversal (bug). This allows me to kill the live stream and keep the dvr stream going. Of course I loose my httpprovider.
Obviously that is a sucky way to get something that is sitting right on the file system.
PLEASE!!!! DVR-ed content should not be coupled to live streams!