Click on the Advanced tab, then on the button that says "Make Firefox the default browser". You can also check the box that says "Always check..." I don't use Firefox much at all so I don't have it checked.
At least he didn't say Chrome was his default by choice.
At least that didn't happen. I'd have stripped and ran around the block laughing, and that wouldn't be good for anyone except the people collecting citation dollas.
No, the reason for that is that FB constantly change the way embedding works and this here is old. New forum will, which reminds me I should get to it.
I don't know what it's being used for. Dudeguy asked me about it and I said it sounds like something you could google but I'll go ahead and ask my brilliant friends.