Rik,
the action is a broadcast all filtered by tag/layer
you do not need to put gameobject.. if you need to send to a gameobject, you do not need tag/layer as you already know your 'target'.
if the event name is not in the dropdown (not global, can't seem to make the drop-down show all global events) then key input (use copy/past) the event name. The broadcast (send event) is always global..
You would use this action if for example I have 100 gameobjects all with the same event (set to global) name in them (and set FSM name). I want to quickly send an event to 25 gameobjects, I use the tag filter as my 25obj out 100 have a different tag... when i need to send to all 100 gameobject, i would then use the 'send event' action set (the normal one by playmaker) to broadcast all. Anyway, this is how i use it...