Brainstorm an idea as the video suggests: write down all your ideas and keep a written record of them until you have developed a solid plot, setting, and characters for a ten-minute, one-act play. A good play has a conflict that eventually is resolved (or reaches at least a partial resolution or change of some kind). For example, in Beyond the Horizon we learn in Act I, Scene I about some conflicts between brothers Robert and Andrew. They do not understand each other’s dreams as they have different values. Additionally, they are both in love with Ruth. In your play, you'll want to start with a conflict that can arrive at some degree of resolution in just one act.