How can you tell when YouTube is actually 'Live'...

I'm watching... but is it live? I've seen many of these and it can say 'live' on the screen when it's not.... is the red progress line an indication? When it's all the way right and not 'progressing' are you actually live?

There is also a 'live' button???? on the bottom.... but I've seen that before when you're watching is NOT live.

And yes, I know this is a dumb question for you YouTube pros but unfortunately I'm not too savvy when it comes to YouTube. - JamesJM