Making Product Demo Videos with Codex: The Coworker Desktop App Demo

Melvin Vivas · X video post · 2026-09-10 · 0:30 · 1,019 views · Open on X

Topics: AI Dev Tools & Productivity, AI Agents, Tool Use & MCP · Level: beginner

Summary

Melvin Vivas shares a 30-second demo video he made with OpenAI's Codex. It shows Coworker, his local-first desktop app of AI coworkers. In the demo, a user picks an AI coworker from a dashboard, asks it for an invoice, and gets back a finished PDF to review. The post mainly shows a coding agent producing a narrated demo video. He notes one flaw: the voiceover mispronounces "PDF" at the end.

Key points

• The creator used Codex, a coding agent, to produce a narrated product demo video and calls the process 'addicting'.
• The result was nearly usable as-is. The only flaw he mentions is the narrator mispronouncing 'PDF' at the end, so check the generated voiceover for problems with acronyms and terms.
• Coworker is pitched as 'Local-First AI Coworkers for Desktop': AI agents that run on your own machine.
• Demo flow: a dashboard brings everything together, you choose a coworker, give it a task (for example 'need an invoice'), add details in a conversation, and get a finished PDF ready to review.
• The product's main idea is turning a chat conversation into a finished document, with 'less repeating, more doing'.

Resources mentioned

• Coworker (donvito/coworker) · repo · github.com · free
  The creator's local-first desktop app where you pick an AI coworker and have it produce work such as invoices as finished PDFs.
  Also in: Claude Opus 5.5 for Video Making: Creator's Showcase Thread (Coworker) (Melvin Vivas on X · notes), Coworker: free open-source desktop AI coworker app (Melvin Vivas on X · notes), Coworker: Open-Source Desktop App for AI Agents (Melvin Vivas on X · notes), Using Devin AI to Test the Coworker Desktop App on Windows (Melvin Vivas on X · notes) and 38 more
• OpenAI Codex · tool · openai.com · paid
  OpenAI's coding agent. In the diagram it writes code, fixes review findings and drives the build loop. The creator also used it to make this video.
  Also in: An agent bot that installs and drives Codex on its own (Melvin Vivas on X · notes), Asking a Coder bot to install Codex (Melvin Vivas on X · notes), Sign in with ChatGPT: Setting Usage Limits for Each App (Melvin Vivas on X · notes), Codex Cloud Environments Must Be Saved & Published Before Use (Melvin Vivas on X · notes) and 240 more

Try this

• Try using Codex or a similar coding agent to make a short narrated demo video of your own project.
• Check the generated narration for mispronounced acronyms and terms (such as 'PDF') before you publish.
• Build a local-first desktop app with an AI 'coworker' that turns a chat conversation into a finished document, such as an invoice PDF.
• Set up an agent workflow that automatically makes a narrated product demo video for a portfolio project.