Sony DVD plays, Warner Bros no play...why?
 

Xine on Slackware 10
Xine worked perfectly with a Sony DVD without installing
libdvdcss. All I had to do was modify the /root/.xine/config
file so that audio would use /dev/cdrom and the Sony DVD
ran perfectly with excellent sound. So, thinks I, DVD is mine!
Not so!
I then tried a Warner Bros DVD and absolutely nothing happened
except a nagging "NAV packet error". To solve this I had to
download libdvdcss and install it and do the command "ldconfig".
Now it works.
Could anyone tell me why a Sony DVD would work without
libdvdcss and not the Warner Bros DVD? Does Sony have
something special the other DVD does not?

It seems that Sony does not use CSS to encrypt the DVD, therefore it played without deCSS