Any active WS, BLS, or RS, in a live feed where any player in game can spectate only while said activity is actively happening.
Why? It's the reason why some keep asking for Galaxy chat: to know there are players doing stuff, in-game. As has been requested multiple times by the devs: ask about and speak about what the problem is.
So since the one of the problems created by losing Galaxy chat is we no longer see the activity in the game at large I offer the suggestion to show some activity: show the stuff that is happening in the game in real time.
This has the benefit of any player at any time having access to something in-game that shows them there's stuff happening.