re: To make sure a problem remote is working?
Just because I see a bright spot on my cell phone doesn't mean the remote is "working". It may be transmitting, but it may not be changing my channels. I'd know it was transmitting, but I wouldn't know if it was coded correctly for the device or even sending out the correct codes if it was.
So, while this test could indeed tell me if the batteries and/or remote itself was dead, it wouldn't really tell me if it was "working".
For now, I'll consider it a parlor trick, something to share with the kids, which I did.