I have been struggling with copying a DVD in Linux. I like to copy the ones I purchase in case they get damaged.
In any case, copying a dvd in kubuntu (or ubuntu) requires the installation of libdvdcss2, which isn't easily found.
I finally found the answer here:
Using the following lines, the library is installed and K3b (and other applications) can read an encrypted DVD.
sudo apt-get install libdvdread3 debhelper fakeroot