From my read, the difference between "Broadcast Living Stories" and the regular ones is that you can trigger a broadcast manually instead of the character having to run over it in a branch. The interface tells you how many characters qualify for the qualities you specify.[li]
Does this remain in effect for anyone who achieves that quality set while the broadcast is active? (Say if someone achieves 10 Dark Secrets" anywhere in the game I can activate something no matter what part of the game they are in…or does it only trigger for the people who qualify when I activate it by manually hitting the button?