You might have urpmi installed but are you using it to install packages, rather than compiling from source?
Have you set up the urpmi sources as described on plf or
www.urpmi.org
Menu > System >configuration > Packages > Software Media Manager
Will show you what sources you have installed.
libdvdnav0-0.1.9-2mdk is I think from one of the contrib sources
libdvdcss2 is available from plf, you will need this to watch encrypted dvds
Installing packages from source rpm or tar balls is a very useful skill, just not a nice thing if you are in dependancy hell.