Download Helper can only save HTTP videos, it doesn's support even the regular RTMP protocol, I'm not even talking about Adobe secure RTMP measures (RTMPE).

As for Replay Media Catcher, please read the following:
As of January 28, 2009, any newly installed copy of Replay Media Catcher does not support Adobe Secure RTMP Measures.


Related thread:
RTMPE stream recording/downloading/capturing/ripping/saving