Note: Because this addon utilizes the latest WebExtention and ES6 technologies for efficiency, this addon requires Firefox >= 48. If you have different requirements, please contact me and I'll write a separate version for you. How to watch Netflix on Linux (and other *nixes) Netflix requires additional media playing software called Microsoft Silverlight, which runs on top of the Microsoft .NET framework. In the past, the people at Xararin created an open-source implementation of .NET called Mono that ran an implementation of Silverlight, which they named Moonlight, which enabled you to play Silverlight files natively on any *nix environment. Unfortunately the project is no longer developed which forces us to install .NET and Silverlight in a Windows emulator and tell Firefox to play Silverlight files through that setup. Luckily, it's (usually) not as hard as it sounds!

Install Pipelight. Pipelight is an easy to use installer program for Silverlight and other Windows only browser extensions, automatically installing and configuring WINE, and using NPAPI to seamlessly integrate the extension into your browser. This does not work with browsers which do not support NPAPI, such as Google Chrome. And because this method uses WINE, you will only be able to use this method on 32 or 64 bit x86 platforms.
1. Debian-like/Ubuntu/AV Linux/SteamOS, 64-bit: Enable 32 bit packages. On newer versions of Ubuntu, this is enabled by default but running this command will be harmless.
  sudo dpkg --add-architecture i386
2. Remove any previous versions of Pipelight (just in case):
  - Debian-like/Ubuntu/AV Linux/SteamOS:
    sudo apt-get remove pipelight*
3. Enable / install non-free Microsoft corefonts.
  - Ubuntu/OpenSUSE: Already enabled by default, skip to next step.
  - Debian: Enable the contrib repository:
    sudo sed -i "/^# deb .* contrib$/ s/^# //" /etc/apt/sources.list
    This will enable Debian's contrib repository, which contains many non-free packages.
  - Fedora:
    sudo rpm -i http://sourceforge.net/projects/mscorefonts2/files/rpms/msttcore-fonts-installer-2.6-1.noarch.rpm
4. Add the Pipelight repository key to your package manager keystore:
  - SteamOS:
    wget -O- http://download.opensuse.org/repositories/home:/DarkPlayer:/Pipelight/SteamOS/Release.key | sudo apt-key add -
  - Ubuntu >= 10.04: This is handled automatically by the apt-add-repository command in the next step.
  - Debian-like/Other Ubuntus/AV Linux:
    wget -O- http://repos.fds-team.de/Release.key | sudo apt-key add -
5. Add the Pipelight package repository to your package repositories:
  - Ubuntu >= 10.04:
    sudo apt-add-repository ppa:pipelight/stable
  - SteamOS:
    echo "deb http://download.opensuse.org/repositories/home:/DarkPlayer:/Pipelight/SteamOS/ ./" | sudo tee /etc/apt/sources.list.d/pipelight.list
  - AV Linux:
    echo "deb http://repos.fds-team.de/stable/debian/ avlinux main" | sudo tee /etc/apt/sources.list.d/pipelight.list
  - Debian >= 7.0:
    echo "deb http://repos.fds-team.de/stable/debian/ $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/pipelight.list
6. Update your package index:
  - Debian-like/Ubuntu/AV Linux/SteamOS:
    sudo apt-get update
  - OpenSUSE:
    sudo zypper ref
  - Fedora:
    sudo yum check-update
7. Install Pipelight (this will also install WINE):
  - Debian-like/Ubuntu/AV Linux/SteamOS:
    sudo apt-get -o Dpkg::Options::="--force-overwrite" install --install-recommends pipelight-multi
  - OpenSUSE:
    sudo zypper install pipelight
  - Fedora:
    sudo yum install pipelight
Configure Pipelight.
1. Update Pipelight plugin cache:
  sudo pipelight-plugin --update
  Re-run this command any time you wish to check for plugin updates.
2. Enable + configure Silverlight:
  sudo pipelight-plugin --enable silverlight
  This command will require you to accept two different licenses. Type 'Y' to continue. If you do not accept the licenses but continue anyway, you are now a pirate. Ahoy Matey! Run this command again for any other plugins you wish to enable.
3. Install Pipelight's NPAPI browser plugin into Firefox:
  1. First, close all running instances of Firefox (important)!!:
    sudo killall firefox
  2. Then run this command:
    sudo pipelight-plugin --create-mozilla-plugins
4. Launch Firefox. Silverlight should now be installed and ready to go. Use a simple Silverlight test such as... this website. If you see a bunch of balls bouncing around then congratulations, Silverlight (at least features from 2.0) is now enabled in your Firefox browser! If there's a problem then contact me and I will try my best to help sort out the problem.
One last step: Install this addon! Some websites that use Windows plugins will block Linux users because they're a bunch of greedy big-business meanies. Typically you will need to install a user switcher agent to trick those websites into thinking you're on a Windows machine by spoofing your User Agent string for specific websites. Or if you're just interested in watching Netflix, please install this addon instead. You can install it and hopefully forget about it! I will try my best to update this addon to be compatible with newer versions of Firefox and continue to trick Netflix whenever they update their Linux detection abilities.

Happy Netflix viewing :D