Facebook doesn't require you to prove you have a license before posting. They just require you to have a license before posting. They will ask for that license

Facebook doesn't require you to prove you have a license before posting. They just require you to have a license before posting. They will ask for that license if a copyright holder files a claim. The first activity you describe is legal because a special copyright licensing regime applies to derivative musical works like strumming a tune in your guitar, so you could also steam your guitar cover of the popular song on YouTube without issue, even for commercial use. (And thousands of musical performers do, without issue.) The second activity is part of the implied license granted by physically owning music on a licensed media like a CD. Unlike the first activity, there isn't a special licensing regime and so streaming that music online requires it's own manually acquired license... Even for non-commercial use. The license costs a few cents... Facebook's rules aren't any more restrictive than they've always been. They're just letting you explicitly know what they have always been. (I handled music licensing at my old job and we were a Facebook video partner back in the day so I'm very familiar with how the musical licensing works in the US.)