Yea, it is most likely to do with what format the DVD player can read. My nicer 5-DVD changer will play some VCD's (SVCD I believe), but will not play others.
My very cheapy DVD player in the bedroom will actually play much more - all the VCD formats plus more.
(hide) If you want to play a game with an opponent of a similar level, you can define a required BKR range for a new game invitation. Then nobody with a BKR outside this range will be able to see/accept it. (Katechka) (show all tips)