I did not go looking for the DVR manual but in the past this was done by unplugging the HDMI connections and using the old red, white and yellow plugs from the dvr to the recorder. You would monitor the play on an now older composite TV and then play the content and press record on the recorder.
This really challenges folk today and may no longer be possible.
Need help. How do you record from a program you recorded from DIRECTV DVR HR54-500 to a Magnavox DVD player?