Ok - I got it working. Heres what I did.
In the basement where this is going, I have an H25 box as I said. It is setup with the RF antenna and mounted behind my TV. This receiver should have been capable of programming this remote, but I didn't have luck. Upstairs, I have an H24. I brought my soundbar up there and brought up the RC65RX remote. I went through the programming process up stairs. On the H24, it not only asks you for a make (Samsung) but also a model number (HW-FM45C). This model number, of course, is not in the list. I selected 'don't know my model number' instead.
The receiver said to point the remote at the receiver at which time it programmed the remote for me. The first code did not work, so I selected 'next code' and it programmed the remote again. This, I assume is what people mean about the 2 way communication and the receiver programming the remote - the H25 may not have this capability (mine downstairs did not do this).
On the second shot, it worked. I was able to kill the power to the soundbar using the RC65RX. I then locked the volume in so when the remote is in the normal mode it turns on the TV/cable box but uses the soundbar for volume controls.
I went back and pulled the code off of the remote - the code it used for the HW-FM45C was 32660
I confirmed this by hand programming the 32660 code into the AV2 spot - and that worked as well.
From what I understand the 65RX may not have this code available to it without getting it from the cable box - I don't know. All I know now is that the remote has the information it needs.
As it stands now, I can use the 65RX to turn on the cable box, TV.... switch the switch to AV1, turn on the soundbar, then switch back to the directv and control the soundbar volume and cable box with the remote.in that mode. This is exactly what I wanted. The sound bar is only connected via optical cord which makes it much easier to hide (vs the 2 HDMI cord option)
Hope this helps someone - I was inches away from returning this soundbar.