Comment 8 for bug 1777070

Yes, this fixed it for me, too, but I couldn't get it to work, just on the explanation above. Here's a little more detail. Follow the instructions at:

https://forums.linuxmint.com/viewtopic.php?t=295649#p1644426

Worked on Firefox Quantum 69.0 (64-bit) on Ubuntu 18.04.3 LTS bionic.

Now I can watch the Great Courses and other movies on Kanopy for free through my local library account. Yay! Only 6 hours after my first attempt, LOL.