On a trusted website, for a class which I paid a lot of money to attend, I get this error message, on FireFox only: The media could not be loaded, format is not supported. I used to LOVE Firefox,but I'm getting frigg'n irritated by it right now. Chrome and Safari both open this page. I had this same problem a few days ago, was sent a long list of possible ways to deal with it that were all over my head complicated. I chose the simplest one- to clear caches, and it worked! yay, for a couple of days, now the error is back. I there must be a different solution , or cause, than the cache one - What needs to be turned on or off, so this doesn't happen? Too complicated, too frustrating. I'd love it if someone could give me some more ideas on this. Macbook Pro 16" 2021, IOS Monterey 12.1 Thank you!