Various aspects of the subject technology relate to systems, methods, and machine-readable media for video generation. An input video can be provided to a video server that is coupled to a video database storing hundreds, thousands, millions, or billions of video clips. Each stored video clip includes content that is known to the video server. The video server identifies aspects of the content of the input video and identifies matching video clips stored in the video database, using a trained machine-learning engine. The machine-learning engine can also modify some aspects of the input video while maintaining other aspects of the input video.