by-lua/video-editing

Watch Video

Claude can't stream video directly. This skill fakes it: a Python pipeline (vendored from bradautomates/claude-video under scripts/) downloads the video, extracts auto-scaled JPEG frames with ffmpeg, pulls a timestamped transcript (native captions first, Whisper API fallback), and prints a markdown report listing every frame path. Claude then Reads each frame, aligns it to the spoken text, and writes a structured notes file.

When to invoke

Slash-command only. Run this skill ONLY when the user literally types /watch-video. That is the sole trigger.

Do NOT invoke on:

• Casual phrases like "watch this video," "summarize this," "take notes on this YouTube video," "analyze this reel"
• A bare YouTube URL pasted with a question ("what useful tips are in this video?" + URL)
• Any natural-language ask about a video that lacks the explicit /watch-video command

Default for YouTube questions without the slash command: pull the transcript the fastest way available — fetch the YouTube page / use yt-dlp captions / a transcript site — skim it, and answer from that. The frame-extraction pipeline is overkill unless the user explicitly asks for it via /watch-video.

If you'd rather have auto-trigger behavior, edit the description: line above to match the keywords you want Claude to fire on (e.g. "Use when the user wants Claude to watch, analyze, or take notes on a video"). Slash-only is the default in this repo because explicit invocation prevents accidental token burn on long videos.

Dependencies

• ffmpeg + ffprobe on PATH — for frame and audio extraction
• yt-dlp on PATH — for downloading and caption fetching
• Python 3.9+ — the bundled scripts use from __future__ import annotations so 3.9 works
• Optional: Whisper API key for videos without native captions. Set GROQ_API_KEY (preferred — cheaper/faster, runs whisper-large-v3) or OPENAI_API_KEY in ~/.config/watch/.env. Without one, captioned videos work fine; uncaptioned videos return frames-only.

Run python scripts/setup.py --check to verify dependencies, or python scripts/setup.py to scaffold the .env and check binaries. On macOS, the installer auto-installs missing binaries via Homebrew. On Linux/Windows, it prints exact install commands.

Pipeline

The work happens in scripts/watch.py. It downloads, extracts, transcribes, and prints a markdown report to stdout that lists every frame path. The pipeline auto-scales the frame budget by duration (hard cap 100 frames / 2 fps), so no manual interval tuning.

python scripts/watch.py "<youtube-url-or-local-path>" [flags]

Flags worth knowing:

• --start T / --end T — focus on a section (SS, MM:SS, or HH:MM:SS). Auto-scales fps denser inside the range. Use this for any question about a specific moment, or for any video > 10 min where the user's question is about one part.
• --max-frames N — lower the cap for tighter token budget (default 80, hard max 100).
• --resolution W — frame width in px (default 512; bump to 1024 only if on-screen text is unreadable).
• --whisper groq|openai — force a specific Whisper backend (default: prefer Groq if both keys exist).
• --no-whisper — skip transcription entirely if no captions. Frames-only output.
• --out-dir DIR — keep working files somewhere specific (default: an auto-generated tmp dir).

Auto-fps budgets (full-video mode):

• ≤30s → up to 30 frames
• 30s–1min → ~40 frames
• 1–3min → ~60 frames
• 3–10min → ~80 frames
• >10min → 100 frames sparse (warning printed; consider --start/--end)

Step-by-step workflow

1. Run the pipeline

Default invocation, no flags:

python scripts/watch.py "<source>"

For long videos where the user asked about a specific moment, pass --start/--end:

python scripts/watch.py "<source>" --start 2:15 --end 2:45

The script writes everything to a tmp working directory and prints a markdown report to stdout. Capture the stdout — it contains:

• Header (Title, Uploader, Duration, Transcript source: captions / whisper (groq) / whisper (openai) / none available)
• ## Frames section with - \` (t=MM:SS)` lines
• ## Transcript section with [MM:SS] text... lines
• Footer with Work dir: <path>

2. Read every frame

Read all the listed frame paths in a single message (parallel Read tool calls). The Read tool renders JPEGs as images. Each frame's filename + t=MM:SS from the report tells you when it occurred — pair each frame with the matching transcript line at that timestamp.

For very long videos (>10 min, sparse mode): the budget already capped at 100 frames, so reading all of them is fine.

3. Write the summary

Output file: <work-dir>/<slug>-notes.md by default. If the user said "save notes somewhere permanent," ask where.

Structure the markdown like this:

# <Title>

**Source:** <URL or local path>
**Duration:** <mm:ss>
**Uploader:** <if from YouTube>
**Transcript source:** <captions / whisper (groq) / whisper (openai) / none>

## One-line summary
<≤20 words — the core claim or hook of the video>

## TL;DR
<3–5 bullet points capturing the main arguments, moments, or beats>

## Timeline
- **[00:00]** <what's happening visually + the key line being said>
- **[00:15]** ...
<one row per meaningful beat, not per frame>

## Key quotes
> "<verbatim quote>" — [mm:ss]

## Visual notes
<what the video shows that the transcript alone would miss — setting, B-roll, on-screen text, graphics, transitions, subject's emotion>

## Takeaways (optional)
<Only include if the content is directly relevant to the user's domain or goals. Omit otherwise.>

4. Clean up

After the .md is written, delete the work dir (it contains the full downloaded video + frames, which is large). The script prints Work dir: <path> in the footer of its report; pass that path to rm -rf.

If the user specified a non-tmp --out-dir, ask before deleting.

Common gotchas

• YouTube Shorts / age-gated / members-only — yt-dlp may fail. Surface its stderr verbatim; don't retry silently.
• No captions + no Whisper key — the report says Transcript: none available and points at setup.py. Tell the user they can add a Groq key to ~/.config/watch/.env for Whisper, or use --no-whisper for frames-only.
• Local file with no audio track — Whisper extraction errors out cleanly. Use --no-whisper for frames-only.
• Very long videos (>30 min) — confirm with the user before running. The pipeline caps at 100 frames so the budget is bounded, but a sparse 100-frame scan of a 60-min video isn't very useful. Almost always better to run focused on the specific section.
• Cloudflare 403 on Groq — whisper.py already sets a custom User-Agent to clear Cloudflare's default-Python-UA block. If you ever see a 403, that's the failure mode.
• No automatic Groq → OpenAI fallback — the script picks one Whisper backend at the start of each run (Groq if its key is set, else OpenAI) and stays on it. If Groq rate-limits, the script retries Groq twice then errors out. To use OpenAI instead, pass --whisper openai.

What NOT to do

• Don't attempt to "watch" a video by inventing content based on title or thumbnail. If the pipeline fails, say so.
• Don't write the summary before actually reading frames. The transcript alone misses visual context (B-roll, on-screen text, emotion, graphics, transitions).
• Don't skip cleanup. Frame dumps + downloaded videos are large.
• Don't auto-fire on a video URL. Slash-command-only — see "When to invoke" above.

Engine attribution

The pipeline scripts under scripts/ are vendored from bradautomates/claude-video (MIT). See THIRD_PARTY_NOTICES.md for the full upstream license.