I'd tried this before, with no success, but your post encouraged me to try again, and this time it worked. The crucial difference was that the TV needs to be set (on the TV itself, not by the remote) to the channel not used in one's area--I believe it's always either channel 3 or channel 4. On the remote, channel 3 is just an ordinary channel: NBC in my case. But on the TV itself it's blank, and a VCR can play its tape there.
I actually use my VCR as the TV tuner, in one TV set-up, but that's irrelevant. All I said above worked on another TV, which isn't connected to the wall in any way, only to the VCR, since no TV signal is available. (Comcast would sell me another, but I don't need more than the two that come standard.)
Thanks for getting me started on this again--your solution was basically right.