I know how rudimentry this question is, but are you sure the first DVD was GWTW and the second had anything on it at all? Was the first one a store-purchased copy of the movie or one that you or someone else had recorded?

@elbanditoroso I completely agree.

@Pachyderm_In_The_Room Yes and Yes. They both play in the bedroom. Obviously the first DVD was GWTW because it played the great soundtrack. I might just give up.

It’s possible it’s easy to fix if you’re willing to open the case.

I will conjecture it’s the connection on the cable that’s connected to the DVD super-drive.
Reseating that connector can bring the drive back to life.
Especially if you can put the disc in, it spins a bit, then it is kicked back out.
That means it’s getting power and its autonomous features are working.

The connections can get oxidized and just sckuffing the connector off and back on a couple times can get the connections working again.
My 3-year old mac mini needed that for the first time about a month ago and it’s a common problem in any type of computer.

I found a youtube that addressed opening the model I have. Look for “open the case on IMAC model <xyz>”

Is an updated driver needed? Perhaps the encryption key was changed, due to piracy? That happened with my Sony BD/DVD player.

Try VLC to play it back.

I’m not sure if it is a software or hardware problem. It is totally within reason that the DVD drive took a shit. The one in my iMac did after a few years.

If VLC can’t play it back it might be time to get a cheap usb drive like this. It will be a hell of a lot cheaper then getting the drive in the iMac fixed. The local shop wanted around 150 to replace mine.

I downloaded VLC, @johnpowell but it didn’t work. GWTW still plays the soundtrack but not the movie.
@dabbler I’d be terrified to open the case if I could actually do it.