Install DVD decryption library script

wget https://raw.githubusercontent.com/panticz/installit/master/install.libdvdcss.sh -O - | bash -

#!/bin/bash

# add repository
echo "deb http://download.videolan.org/pub/debian/stable/ /" | sudo tee /etc/apt/sources.list.d/libdvdcss.list

# get keyring
wget -O - http://download.videolan.org/pub/debian/videolan-apt.asc | sudo apt-key add -

# update repository
sudo apt-get update -qq

# install libdvdcss
sudo apt-get install -y libdvdcss2

Other method:
sudo apt-get install ubuntu-restricted-extras
sudo /usr/share/doc/libdvdread4/install-css.sh

Links
http://download.videolan.org/pub/libdvdcss/