I'm still waiting for them to support Firefox and Linux. Their support says they are working on it, but I am positive that is a lie. At least I can work around it by masking my user-agent string as Chrome (DRM needs to be enabled).
Netflix works on Firefox. I don't remember about Linux. ~3 years ago yes Netflix wouldn't work on Linux without plugins, but I thought they fixed it or provided a workaround.
Nope, you have to do a user agent string to get around it. From what I can tell Netflix is filtering it. But I may be wrong, I'm not sure how this stuff works. But I can do it on Firefox and Linux as long as I have DRM enabled (the change in FF49+) and change my user agent string to Linux Chrome (see image http://i.imgur.com/twjpXgv.png). It WILL NOT work without changing the user agent string.
Talking to their support Netflix says it is FF's problem. From what I can tell it isn't actually FF's problem anymore (because this wouldn't work, right?).