Hello, I am unable to play certain video on Firefox version 86 on my Macbook Pro 13-inch, 2017, running Big Sur 11.3 Beta (20E5196f), which I just updated my system to today. These sites are working in Safari '''I tried installing the previous Firefox version, version 85, these sites worked on this version!''' This problem only occurs on Netflix, Prime and Disney Plus. Other video sites like Youtube and Crave TV are working. This same problem occurred a few days ago, before I updated my computer, but I was able to resolve it by clearing cookies and cache in firefox, this no longer works. On Netflix, preview videos that appear when hovering over a selection do play, but when trying to play an actual title I get error code f7121-1331 On Prime I get a message saying We're experiencing a problem playing this video. For assistance, please go to www.primevideo.com/help. On Disney Plus I get error code 83 I have tried on the advice of other posts to clear cache and cookies, disable all add-ons, checking if certain media options are enabled in About:config, restarting my computer and firefox, and resetting Firefox twice. None of these have worked for me. The only thing that worked was installing and using the previous Firefox version 85.