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.
npx skills add bcastelino/agent-skills-kit --skill video-downloadergit clone --depth 1 https://github.com/bcastelino/agent-skills-kitWrote 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.
[](https://agentmods.dev/skills/bcastelino/agent-skills-kit/video-downloader)<a href="https://agentmods.dev/skills/bcastelino/agent-skills-kit/video-downloader"><img src="https://agentmods.dev/badge/skills/bcastelino/agent-skills-kit/video-downloader/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.
<a href="https://agentmods.dev/skills/bcastelino/agent-skills-kit/video-downloader"><img src="https://agentmods.dev/badge/skills/bcastelino/agent-skills-kit/video-downloader.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00075 | $0.00696 |
| Opus 5 | $0.00037 | $0.00348 |
| Sonnet 5 | $0.00015 | $0.00139 |
| Haiku 4.5 | $0.00007 | $0.00070 |
Grade A, and why
video-downloader 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 11d 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.
This is a copy
91% identical to youtube-downloader — 11 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.
YouTube Video Downloader
Download YouTube videos with full control over quality and format settings.
Quick Start
The simplest way to download a video:
python scripts/download_video.py "https://www.youtube.com/watch?v=VIDEO_ID"
This downloads the video in best available quality as MP4 to /mnt/user-data/outputs/.
Options
Quality Settings
Use -q or --quality to specify video quality:
best(default): Highest quality available1080p: Full HD720p: HD480p: Standard definition360p: Lower qualityworst: Lowest quality available
Example:
python scripts/download_video.py "URL" -q 720p
Format Options
Use -f or --format to specify output format (video downloads only):
mp4(default): Most compatiblewebm: Modern formatmkv: Matroska container
Example:
python scripts/download_video.py "URL" -f webm
Audio Only
Use -a or --audio-only to download only audio as MP3:
python scripts/download_video.py "URL" -a
Custom Output Directory
Use -o or --output to specify a different output directory:
python scripts/download_video.py "URL" -o /path/to/directory
Complete Examples
- Download video in 1080p as MP4:
python scripts/download_video.py "https://www.youtube.com/watch?v=dQw4w9WgXcQ" -q 1080p
- Download audio only as MP3:
python scripts/download_video.py "https://www.youtube.com/watch?v=dQw4w9WgXcQ" -a
- Download in 720p as WebM to custom directory:
python scripts/download_video.py "https://www.youtube.com/watch?v=dQw4w9WgXcQ" -q 720p -f webm -o /custom/path
How It Works
The skill uses yt-dlp, a robust YouTube downloader that:
- Automatically installs itself if not present
- Fetches video information before downloading
- Selects the best available streams matching your criteria
- Merges video and audio streams when needed
- Supports a wide range of YouTube video formats
Important Notes
What ships with it
1 file 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.
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.
- 11d ago First seen · 99 lines · 75 tokens per session scan A 669ac7af51c7
video-downloader is a skill published in the GitHub repository bcastelino/agent-skills-kit (2 stars, last pushed 1mo ago), licensed MIT. It adds 75 tokens to every session and 696 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to youtube-downloader, differing in 11 lines, and is treated as a copy.
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