I can't play drm-protected content from online movies in Ubuntu 13.10.
Anything that work before as workaround not work anymore.
I tried reinstall adobe flash player - still not working.
This worked for me http://ubuntuforums.org/showthread.php?t=2144347 (using 13.10 and Chromium). Not sure if it works for Firefox, but it should.
Basically, you need to install HAL manually, since it isn't in the repository for 13.10.
It seems Ubuntu's default configuration makes Flash's DRM not work. Try this article's instructions.
Open terminal and paste commands
sudo apt-get remove flashplugin-installer
is important to restart the system before the next step.
sudo apt-get update sudo apt-get install flashplugin-installer
If you do not restart after first command it does not work
These instructions were not quite enough for my installation. My system also had apparmor active and the default Ubuntu configuration for Firefox prevented DRM content from displaying properly in Firefox. The solution was a different apparmor profile for Firefox as outlined here: http://rookcifer.blogspot.com/2012/09/custom-firefox-apparmor-profile-for.html