The usage of wget getwidevine.sh, which is referenced in many forums delivered only an
outdated libwidevine for ARM-boxes.
I haven't even tried to get Netflix or Amazon on my S905x box yet, but will soon. I looked into the script referenced in many forums and saw that it downloads an Arm7h package of chromium-widevine. Googling found an updated version on the ArchLinux website and instructions for Netflix.
Hope this helps; I'll be testing this sometime soon when I have free time.