Just tried the preferences in the lastest Firefox.
Did the same thing: acts like it recognizes the provider, shows current live features.
As soon as I click on one, the flash video screen spinner acts like it is going to load, but the spinner just spins.
I have searched some of the Linux help forums and that seems to be the likely result. It is funny that NBCSports will play, but FoxSportsGo won’t.
Not sure if these instructions are applicable anymore, but I had to install HAL-flash in order to get HULU to work, from here:
https://askubuntu.com/questions/799481/how-to-install-hal-in-16-04lts