Write the concept
Open the rap video maker and describe one scene: a subject, a setting, an action. "A hooded rapper on a rain-soaked rooftop at night, neon signs behind him, slow dolly-in" is a complete brief. Working from a song? Paste the two or four hardest-hitting lines of the hook — bars with concrete images (places, weather, objects) translate best to video. Want to star in it? Upload a photo instead, and the person in the picture becomes the performer.