A rule for automatically creating a walkthrough video of a local web app by controlling it with Playwright and assembling the recording with ffmpeg. It covers planning scenes, recording the real app, adding overlays, and checking the final video.

Making product demos, feature walkthroughs, and localhost screen recordings, including scripted scenes, loading states, captions, cursor movement, and final video assembly.

It provides a repeatable way to show a feature working without manually recording the screen, while preserving the app’s actual interactions.

demo-video — Cursor rule for Cursor by Kminer2053

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo

git clone --depth 1 https://github.com/Kminer2053/demo-video-skill

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/rules/kminer2053/demo-video-skill/demo-video/github.svg)](https://agentmods.dev/rules/kminer2053/demo-video-skill/demo-video)

Your own site

<a href="https://agentmods.dev/rules/kminer2053/demo-video-skill/demo-video"><img src="https://agentmods.dev/badge/rules/kminer2053/demo-video-skill/demo-video/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/rules/kminer2053/demo-video-skill/demo-video"><img src="https://agentmods.dev/badge/rules/kminer2053/demo-video-skill/demo-video.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 54 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 411 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00054	$0.00411
Opus 5	$0.00027	$0.00205
Sonnet 5	$0.00011	$0.00082
Haiku 4.5	$0.00005	$0.00041

Measured 10d ago against content hash 3319ce1afb17, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

demo-video scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/demo-video.mdc · 30 lines

What it actually says

Demo Video (Playwright + ffmpeg)

When the user wants a demo video / feature walkthrough / product demo / screen recording of a localhost app — even phrased as "make something that shows this feature running" — drive and record the real running app headlessly with Playwright and bake in overlays in code. This is for real screen-operation demos, NOT motion-graphic teasers.

Core ideas:

Inject the overlay (subtitle bar, feature label, fake cursor) on document.documentElement (html), NOT body — zoom transforms body, so an html-level overlay is immune to zoom.
A fake cursor (SVG + CSS transition) stages the mouse; the real one is invisible headless.
LLM/loading waits use waitForFunction (never a fixed sleep); record waitMs and speed up only that window 6–9x with ffmpeg.

Workflow (fixed order): script the scene table & get approval → environment check (never kill the user's server) → build ONE PoC scene & get tone approved → capture scenes with scripts/cap_scene.template.js (replace only the SEQUENCE block) → post-process & montage-QA per scene with scripts/postprocess.sh → concat into the montage → confirm with user real playback.

Non-negotiables: ctx.close() before browser.close() (flushes the webm); goto with waitUntil:'networkidle'; speed-up on wait windows is mandatory.

Full detail: read references/playbook.md. Full skill: SKILL.md / AGENTS.md.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

10d ago First seen · 30 lines · 54 tokens per session scan A 3319ce1afb17

Subscribe to this mod's changes

demo-video is a cursor rule published in the GitHub repository Kminer2053/demo-video-skill (20 stars, last pushed 1mo ago), licensed MIT. It adds 54 tokens to every session and 411 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Browser automation Claude Code Creative and media ai-agents automation cursor demo-video developer-tools

demo-video

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

What it actually says

Demo Video (Playwright + ffmpeg)

What this file has done since we first saw it

Other cursor rules, from other repositories

orchestrator-main

orchestrator-sub

extract-frames

audio

display-captions

gif