I believe that a big company like Mozilla, unfortunately, for commercial reasons, have to compromise, not to be excluded from certain proprietary services. After all, there Iceweasel in Debian, which is more "Free-As-In-Freedom" ...
The best way (if they really need it) is to install it the same way Flash player is installed now I guess. They should not install it by default. Yet I can hardly imagine someone watching Netflix movies using Firefox or any other browser. There are set-top boxes for that.