Buttons are like punctuation marks. Like a period, exclamation point, or question mark, a button is a punctuation mark at the end of an act in a show or a scene (or chapter) in a book. To use these in writing treat the end of your chapters like commercial breaks and turn that last sentence into a question mark, or send in the ellipses in that last bit of dialogue, or add a dash that forces the reader to turn the page.