Comment 11 for bug 197068

Same problem with a recent fresh install of Kubuntu Hardy/KDE3. The problem does not appear to be a kernel bug, but a misconfiguration in /etc/udev/rules.d/70-persistent-cd.rules The system-wide fix for this is available here... http://ubuntuforums.org/showpost.php?p=5014367&postcount=4 The Mplayer-specific fixes above also work.

Three months and no progress on this... sounds to me like someone doesn't want Ubuntu users to play commercial DVDs.