problem viewing JW Player video in Firefox
I'm running Firefox 58.0.1 (64-bit) on a Windows 7 64 bit computer. For some reason, I can get JW Player videos to play fine in Chrome, but when I try loading pages like this (https://goo.gl/G3uKe6) in my Firefox browser, the image quickly blinks on the screen, and then it simply becomes a big, black box. This is happening on both of my computers, and I don't have an ad blocker installed. I don't have any browser extensions installed, and I've disabled all plugins / add-ons. How can I fix this?