I haven't watched any of these, but he has assembled quite an impressive list of previous and future guests. What I'm trying to figure out is... how is he doing it? Why are all these people going on?
What do you mean by how is he doing it? He probably asks them if they're interested in talking to him on a Facebook live and they say yes is my best guess. I'm sure he has tons of connections from both being a producer and from hosting his podcast and I don't think general Broadway folks really have anything to do besides participate in livestreams and try to create content in whatever way they can.