Opus 5.5 video tutorial: make a marketing video in Claude Code, step by step

This is the hands-on companion to how Claude Opus 5.5 video generation works. By the end you'll have a finished marketing video rendered on your own computer by an agent running Opus 5.5 — and a file you can re-render for every format and language.

We'll make a 6-second countdown teaser for a product launch, but the steps are the same for any of the free video Skills.

What you need

Claude Code with access to Opus 5.5 (a paid Claude plan or an API key). Codex, Cursor, Gemini CLI and other agents that read SKILL.md work too — see supported agents.
Node.js 20 or newer. Check with node -v.
Google Chrome. The renderer drives Chrome in headless mode. No Chrome? The Skill tells you how to install a headless Chrome build.
A free Reelity account to install Skills.

You don't need FFmpeg: each Skill installs its own copy with npm install.

Step 1 — Pick the model

Start Claude Code in a new folder for your video project:

mkdir launch-teaser && cd launch-teaser
claude --model claude-opus-5-5

Or run /model inside Claude Code and choose Opus 5.5.

Step 2 — Install the Skill

Open the Countdown Teaser page, choose your agent and copy the install command. It looks like this:

npx --yes https://reelity.app/cli/reelity-cli.tgz install event-countdown-teaser --agent claude-code

The first time, the CLI shows a short code and opens reelity.app/connect in your browser; approve it there to connect your account. The Skill is copied to ~/.claude/skills/event-countdown-teaser, where Claude Code finds it automatically. You can also just tell the agent "install the Reelity countdown Skill" and paste the command — it will run it for you.

Step 3 — Describe the video

Write the request the way you'd brief a designer. Include what it's for, the facts, and the formats:

Make countdown teasers for our Spring Launch on 9 April at 6 PM ET — one each for 3, 2 and 1 days to go. Brand colours #0E0E10 and #FF6A3D. Button: "Join the waitlist". I need 9:16 for Reels and 1:1 for LinkedIn.

Opus 5.5 recognises that the Countdown Teaser Skill fits, reads its SKILL.md and follows its workflow. If something is missing — the time zone, the call to action — it asks.

Step 4 — Approve the copy

Before rendering anything, the agent shows you the on-screen text: the event name, the date line, the unit ("days to go") and the button. Fix wording here; it's the cheapest moment to change anything.

Step 5 — Validate and draft

The agent writes an effect.json file and runs the Skill's checker:

node scripts/validate.mjs effect.json

It flags errors (a missing date, an image that doesn't exist) and warnings (lines too long to read on a phone, text that's low-contrast against your background). Then it renders a quick low-resolution draft and a poster image so you can check the timing and look.

Step 6 — Render every format

After you approve the draft, the agent renders the finals — full HD MP4s at 30 fps:

node scripts/render.mjs effect.json --ratio 9:16 --out teaser-3days-9x16.mp4
node scripts/render.mjs effect.json --ratio 1:1  --out teaser-3days-1x1.mp4

For the series, it changes one value (count) and renders again. Three days of teasers in two formats is six files from one conversation.

Step 7 — Localize (optional)

Ask for other markets: "Now make the 9:16 versions in Japanese and German." The agent adapts the copy (not word-for-word), writes the date the way each market does, and renders again. CJK text renders with proper fonts and line breaks.

Troubleshooting

"Chrome not found." Install Google Chrome, or run npx @puppeteer/browsers install chrome-headless-shell@stable and set CHROME_PATH to the path it prints.
Text in the wrong font. Fonts load from Google Fonts during the render, so it needs internet; or name a font installed on your machine.
Image looks boxed. Use a PNG with a transparent background or an SVG.
The agent starts writing its own renderer. Say "use the installed Reelity Skill" — or check it's in ~/.claude/skills.
Text under the TikTok buttons. The templates keep to the platform safe zones; check any frame with the safe-zone checker.