This should work for all Ubuntu linux versions. It’s testet with Linux Mint Mate 17.1 Rebecca.
Install srceensaver packages:
sudo apt-get install xscreensaver-data-extra xscreensaver-gl-extra
Make them usable with Mate:
cd /usr/share/applications/screensavers sudo perl -p -i -e 's/OnlyShowIn=GNOME;/OnlyShowIn=GNOME;MATE;/g' *.desktop
Now you have a big selection of screensavers in your preferences.
Credits to Sergey Potapov and bladerunner6978.