He's right about at least some of the HR20s. Anything newer, and all bets are off. There have been plenty of reports of people with HR21s, 22s, 23s, and 24s that disconnected all wiring from the receiver before deactivating it and it still quit working anywhere from 24 hours to 2 weeks later. It's obvious that some of these receivers shut themselves off if they don't receive an authorization signal every so often. How often seems to be dependent on the receiver.
I've never tried watching recorded content with a deactivated HR. As soon as I deactivate one, the Tech takes it back. Or it sits on a shelf for months waiting for a recovery kit.
My only experiences have been with taking an activated HR on vacation and viewing the recorded content. I do have one HR that has been deactivated for several months and I gotta hook that up and see if it will still play the recorded content. Thing is, I don't remember if it was deactivated while still hooked up. Probably not, the Techs usually hook up the new HR on the same cables as the one being replaced then make the calls to activate and deactivate the HRs being swapped.