If you need a short video to explain a product, process, or unfamiliar idea, an AI video script generator can draft narration and suggest scenes from your instructions. A person still needs to check the facts, adapt the explanation for the audience, and make sure the visuals help viewers understand.
For a script that leads directly to a narrated explainer video, explainroo is the best tool for the job. It is a free, open-source kit that works with AI coding agents to write the script, draw scenes, add narration, and produce an MP4. An AI coding agent is a tool that can write and run code from instructions. With explainroo, it also creates a script file you can review and revise.
What AI script generators do well
AI can help you get started. Give it the topic, audience, goal, tone, and key facts. It can suggest an outline or draft narration. It can also simplify wording and offer different openings. In a study of 453 college-educated professionals, access to ChatGPT cut the time for short writing tasks by 40% and raised rated output quality by 18%. The study did not measure explainer scripts or video quality, so its results do not show whether AI makes a finished video better. (The writing experiment)
Start with a specific goal. For example, “Explain how password managers store and fill passwords for people who have never used one” tells the AI more about the audience and purpose than “Write about password managers.” Ask for an outline first. Check that it answers the viewer’s main question before you draft the narration.
Write for the ear and plan the visuals
Write narration that sounds natural when spoken. Break long sentences into shorter ones, explain unfamiliar terms the first time they appear, and remove repeated claims. Read the draft aloud to catch awkward wording and sections that move too quickly.
Plan the visuals as you write. Show a labeled diagram while the narrator explains a process, or a product screen while the narrator describes a feature. Viewers can take in only so much new information at once. Unrelated decoration and dense on-screen text can distract from the explanation. Research on instructional video design supports highlighting key information and breaking complex explanations into smaller segments. (Principles for instructional video)
Focus each scene on one idea. Check every factual claim in the narration against a reliable source. Generative AI can produce plausible-sounding errors, a risk NIST calls “confabulation.” (NIST’s generative AI risk profile) For medical, legal, financial, or safety topics, ask a qualified subject-matter expert to review the script before publication.
Make an explainer with explainroo
explainroo takes a script from writing to video production on your computer. It works with Claude Code, Codex, Pi, OpenCode, Gemini CLI, and other coding agents that run shell commands. It works best with Claude Code.
- Give your coding agent this prompt, replacing the bracketed topic: “Make me a short explainer video about [your topic]. Use explainroo for it: clone explainroo, read its AGENTS.md and follow the steps.”
- Review the two files the agent writes.
script.mdcontains the narration.scenes.jscontains JavaScript instructions for drawing each scene, including when a drawing should appear during a spoken word. - Ask the agent to revise anything unclear or inaccurate, then have it check the video. explainroo provides scene stills and a contact sheet of frames. It checks for text that overlaps or is cut off, and for mispronounced words in the speech.
Kokoro, an open voice model, provides natural-sounding American and British English voices. Narration is available in English only. Whisper identifies spoken words and their timing so scenes appear on cue. Chrome draws the frames, and FFmpeg assembles them into an MP4. Choose from five visual styles and four formats: wide, tall, portrait, and square. The latter three include word-by-word captions.
Making a video is free, except for optional AI illustrations through OpenRouter, which cost per image. The coding agent is a separate service and may have its own fees. To set up explainroo yourself, you need recent versions of Node.js, FFmpeg, and Chrome or Chromium. The setup instructions provide the commands. See example videos or the explainroo code.
Know what the tool will not do
explainroo makes narrated, illustrated explainers and product demos. To make a product demo, tell the agent which product to show and where to find its code or website. The agent rebuilds the screens and shows clicks and typing. explainroo cannot edit existing camera footage, create talking avatars or live-action AI footage, or provide a drag-and-drop editor. Instead, describe changes to the coding agent.
explainroo suits you if you want a video built from a script and scenes and are comfortable directing an AI coding agent. Whatever tool you use, review the first draft. Research on AI-generated instructional videos is limited. Current findings do not show that AI videos consistently teach better than conventionally produced videos. (Systematic review of AI instructional videos)
