broll-overlay

broll-overlay is a skill for Claude Code from novoads/agent-skills. It costs 128 tokens per session (2,401 once invoked), scanned A, original, MIT.

A video-editing workflow that places silent b-roll, or supplementary cutaway footage, over a finished base video. The base audio continues underneath, while the picture briefly switches to the added clips and the final length stays unchanged.

In plain words
What is it for?
Use it to add timed cutaways to a finished video using its transcript and word or segment timings, while keeping the original voice track.
Why use it?
It adds visual variety without interrupting the existing narration or extending the video. It is designed for a locked, approved video rather than for generating the main footage.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the skills plugin — 17 skills, 1 hook shipped together

Good fit Use it to add timed cutaways to a finished video using its transcript and word or segment timings, while keeping the original voice track.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/novoads/agent-skills/broll-overlay
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.

Any agent
npx skills add novoads/agent-skills --skill broll-overlay
Clone the repo
git clone --depth 1 https://github.com/novoads/agent-skills

Made for: Claude Code.

Or install skills, the plugin that ships this one along with the rest of its 17 skills, 1 hook.

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.

agentmods badge for broll-overlay

README.md
[![agentmods](https://agentmods.dev/badge/skills/novoads/agent-skills/broll-overlay.svg)](https://agentmods.dev/skills/novoads/agent-skills/broll-overlay)
Your own site
<a href="https://agentmods.dev/skills/novoads/agent-skills/broll-overlay"><img src="https://agentmods.dev/badge/skills/novoads/agent-skills/broll-overlay.svg" alt="Measured on agentmods" height="20"></a>
Per session 128 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,401 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00128 $0.02401
Opus 5 $0.00064 $0.01201
Sonnet 5 $0.00026 $0.00480
Haiku 4.5 $0.00013 $0.00240

Measured 7d ago against content hash 0fc0a68dd0c8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

broll-overlay 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 7d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/broll_overlay.py, scripts/test_broll_overlay.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

shared/skills/broll-overlay/SKILL.md · 164 lines

How it starts

The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.

B-roll overlay

Lays silent cutaway clips over a finished base video: the base audio runs untouched underneath, the picture cuts away and returns, and the final duration equals the base duration exactly. That is the whole contract — overlay, never concatenation. A previous run concatenated: 24s for a 15s base, voice dead 12s.

Assembly mechanics live entirely in scripts/broll_overlay.py; this file is judgment only — when to enter, where the windows go, what the user sees first.

Entry condition

Two things must already exist. This skill never generates the base — if there isn't one yet, say so and stop.

  1. A finished, approved base video with exactly one audio stream. Approved means the user has watched it and signed off — b-roll is a polish pass over a locked cut. The script stream-copies one voice track under the picture, so a two-stream base is rejected: ffmpeg -i base -map 0:v -map 0:a:0 -c copy.

  2. Its transcript, with timings. One call to POST /v1/transcripts with the base's jobId (or its assetId if it was uploaded). It returns text, word-level words[] and segments[]timings in SECONDS, which is what the EDL below takes — plus an srt you can ignore here. Price it with the transcript arm of POST /v1/estimates and quote that number, never one from this file. The meter is per minute of source, rounded up from a one-minute minimum, and a repeat of the same source is free, so asking twice costs once. No local install.

    (The captions endpoint still cannot supply this — it burns subtitles into a new MP4 and returns no text or timings, verified 2026-08-04 and re-checked when transcripts shipped. That finding is correct and is kept here so nobody re-discovers it and files a bug against captions.)

    Offline fallback: a local whisper pass (whisper-cli or openai-whisper) still works and is the path when there is no API key or no network. Note whisper reports timings in milliseconds where the API reports seconds, and whisper-cli with no model downloaded returns an EMPTY transcript rather than an error — which reads exactly like a bad render. See README for the model download.

Read the full file on GitHub · 164 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

  1. 7d ago First seen · 164 lines · 128 tokens per session scan A 0fc0a68dd0c8

Subscribe to this mod's changes

broll-overlay is a skill published in the GitHub repository novoads/agent-skills (14 stars, last pushed 12d ago), licensed MIT. It adds 128 tokens to every session and 2,401 once invoked, about $0.0006 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 2026-08-31.

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