I also have the extra disc (supposedly with the Ashes video)from the original Sound and Vision box set which doesn't play in any modern equipment - that's pretty useless.
Actually, it does. Well, the audio part of it, at least. I've tried it in various players and the only one it didn't work in was the one which has decided not to play half of my collection anyway. It's either got something to do with the laser disc formatting or the strange black marks on the back of the CD. It looks like someone flicked paint onto it but it plays fine regardless.
I have to say that my most useless item, though, apart from the few records I have which I can't actually play at the moment, is the AU20 pressing of Changesonebowie. It looks cool, being gold and all, but since I have all the albums, I'm never going to listen to it.
It's got nothing to do with you, if one can grasp it