Yes, they should and my main one does normally play the ones I make from BD movies but the one I just tried from a HD DVD disk wouldn't play for whatever reason. I can probably make a BD disk of it though that works if I ever get more blanks and I guess I'll have to try my older WDTV Live player and see if it likes it or try a different program to make the ISO just in case as I used a older copy of Any DVD to make the ISO. I also have a newer Pivos Aios player and the hacked firmware support for it has been almost as good as it was for the Live, plus Pivos supports all the hacking and mods directly and even hired the guy that is mainly responsible for all the better semi official updates
All I know is life is so much easier since I networked in some kind of media player and got a few big external drive to store everything on and watch when I feel like it.