Didn't watch the video but if you wanted to sync a Boolean all I would do is add a photon view to your gameobject, drag your FSM that stores the Bool into the "Observed" Box of the photon view. Then make sure you have marked the bool as "Network Sync" Ignoring the error it might give you about it. (I think it expects the unity networking, but we are using photon)
Then Provided that the game object is created on all clients, the Bool should be the same for every player.
(I think you might also need to add a "Photon Game object Proxy" script to your object)