It may depend on how the FB account is set up. There are many FB sites, for BBC local radio folk programmes for example, which I can see and play videos on. I don't remember whether I've seen live streams on those, but I think so.

I looked at the Celtic Connections FB site when the concert was still going on, but it required me to sign in. That was in a browser on a mobile phone - it might have worked on a laptop I suppose.