Onboarding Videos

What it does

When your agent uses it

• Onboarding demo clips feel laggy
• A clip is being added/swapped/re-recorded
• Posters and videos drift out of sync

Example prompts

• “welcome”
• “/onboarding-videos”

Requirements

• Node.js
• Pre-approved tools (allowed-tools): Bash(node scripts/optimize-onboarding-videos.mjs:*), Bash(pnpm optimize:onboarding-videos:*), Bash(ffmpeg:*), Bash(ffprobe:*), Bash(npx biome check:*), Bash(pnpm --filter @posthog/ui typecheck:*)

Workflow steps

2 steps, taken from the first numbered list in SKILL.md.

1. 1moov atom at the end of the file. Without faststart the player must read
2. 2Resolution far larger than it renders. The featured slot is never wider than

What it can do on your machine

Read from SKILL.md and the folder at commit a4c32df. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Bash(node scripts/optimize-onboarding-videos.mjs:*)
  • Bash(pnpm optimize:onboarding-videos:*)
  • Bash(ffmpeg:*)
  • Bash(ffprobe:*)
  • Bash(npx biome check:*)
  • Bash(pnpm --filter @posthog/ui typecheck:*)

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • pnpm
  • ffmpeg
  • ffprobe
  • npx
  • brew
  • git

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md. Its commands use pnpm, npx and git, which can reach the network depending on how they are called.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Onboarding Videos loads about 1.7k tokens when it runs. Until then it costs about 132 tokens; SKILL.md has 744 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~132

When it runs · the whole SKILL.md, loaded when a task matches

~1.7k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from PostHog/code at commit a4c32df, republished under its MIT licence (© PostHog). 744 words, ~1,706 tokens.

name

onboarding-videos

description

Add, replace, and optimize the looping demo videos in the onboarding "welcome" bento grid (packages/ui/src/features/onboarding). Covers the ffmpeg compression workflow (the scripts/optimize-onboarding-videos.mjs wrapper), the faststart + right-size best practices that keep playback smooth, the first-frame poster convention, and how to wire a new clip into WelcomeScreen. Use when onboarding demo clips feel laggy, when a clip is being added/swapped/re-recorded, or when posters and videos drift out of sync.

allowed-tools

Bash(node scripts/optimize-onboarding-videos.mjs:*), Bash(pnpm optimize:onboarding-videos:*), Bash(ffmpeg:*), Bash(ffprobe:*), Bash(npx biome check:*), Bash(pnpm --filter @posthog/ui typecheck:*)

pnpm optimize:onboarding-videos          # encode any clip not already optimized
pnpm optimize:onboarding-videos --dry-run   # show what would change
pnpm optimize:onboarding-videos --force     # re-encode all (after changing the target constants)

# clips: moov should print BEFORE mdat, width ≤ 1000:
ffprobe -v trace <clip>.mp4 2>&1 | grep -o -m2 -E "type:'(moov|mdat)'"
ffprobe -v error -select_streams v:0 -show_entries stream=width,height -of csv=p=0 <clip>.mp4

# wiring: a grown MediaId union may need a formatter reflow, so let biome fix it:
npx biome check --write packages/ui/src/features/onboarding/components/WelcomeScreen.tsx
pnpm --filter @posthog/ui typecheck

© PostHog, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .claude/skills/onboarding-videos of PostHog/code.

Open the folder on GitHubat commit a4c32df