Youtube Scrape

Scrape YouTube videos: $ARGUMENTS

$ARGUMENTS should be one of:

• A YouTube channel handle (e.g. @AlanHirsch) or channel ID (e.g. UCxVxcTULO9cFU6SB9qVaisQ)
• --video VIDEO_ID to scrape a single video
• --refresh to re-fetch stats for all existing videos without re-downloading transcripts
• Empty — ask the user for the channel handle

Before Starting

1. Confirm YOUTUBE_API_KEY is set in .env.local — if not, tell the user to add it
2. Confirm yt-dlp is installed (which yt-dlp) — if not, tell the user to install it (pip install yt-dlp)
3. Read {{SCHEMA_PATH}} for the videos, videoSeries table definitions
4. Read {{SCRIPTS_DIR}}/youtube-scrape.ts to understand the existing scrape script

Pipeline Stages

Stage 1 — Fetch All Videos from Channel

1. Resolve channel ID: If given a handle (@Name), call the YouTube Data API v3 channels?part=id&forHandle=@Name to get the UC... channel ID
2. Derive uploads playlist: Replace UC prefix with UU to get the uploads playlist ID
3. Paginate playlist: Call playlistItems.list with maxResults=50, following nextPageToken until exhausted
4. Enrich with details: Call videos.list in batches of 50 (part=snippet,contentDetails,statistics) to get full metadata
5. Delta check: Compare fetched video_id list against existing external_id values in the videos table — only download transcripts for new videos

Stage 2 — Download & Parse Transcripts

For each new video (not already in DB with a transcript):

1. Run yt-dlp --write-auto-subs --sub-lang en --skip-download -o "data/vtt/%(id)s" "https://youtube.com/watch?v=VIDEO_ID" with a 60-second timeout
2. Parse the resulting .en.vtt file:
   • Strip VTT headers, cue IDs, positioning metadata
   • Deduplicate repeated lines (auto-subs repeat heavily)
   • Extract { start, end, text } segments
   • Concatenate into fullText
3. If no VTT file produced, set transcript to null and continue

Stage 3 — Chunk Transcripts for Search

Split each transcript into chunks for embedding/search:

• Target: 500 words per chunk
• Overlap: 75 words
• Stride: 425 words (500 - 75)
• Each chunk gets: chunk_index, text, start_time, end_time, timestamp_url (deep-link to that point in the video)
• Absorb tiny final chunks (< 75 words) into the previous chunk

Store chunks in a JSON field or separate table as appropriate.

Stage 4 — Fetch Comments (Optional)

Call commentThreads.list with maxResults=100&order=relevance, paginating with nextPageToken:

• Handle 403 gracefully (comments disabled) — return []
• Extract: comment_id, author, text, like_count, published_at
• Per-video errors should not crash the pipeline

Database Mapping

Map YouTube fields to the existing videos table:

Key Design Rules

• Idempotent — Use upserts keyed on external_id. Safe to re-run.
• Resume-safe — Skip transcript download if VTT file already exists in data/vtt/
• Incremental — Only download transcripts for new videos. Always refresh stats.
• Graceful degradation — 403 returns []; per-video errors don't crash the pipeline
• All timestamps UTC — ISO 8601 throughout
• Batch operations — 50 per YouTube API call; small delays between yt-dlp downloads

Running

pnpm youtube:scrape -- --channel @AlanHirsch
pnpm youtube:scrape -- --video dQw4w9WgXcQ
pnpm youtube:scrape -- --refresh

Output Format

## YouTube Scrape Report

### Channel: [name] ([handle])
### Videos found: N total, M new

### Stage 1 — Metadata: OK
- Fetched: N videos
- New (not in DB): M

### Stage 2 — Transcripts: OK
- Downloaded: X
- Skipped (already exists): Y
- Failed (no subs): Z

### Stage 3 — Chunks: OK
- Total chunks: N across M videos

### Stage 4 — Comments: OK / SKIPPED
- Fetched: N comments across M videos

### Database:
- Upserted: N videos
- Stats refreshed: M videos

### Warnings:
- [any non-blocking issues]

Quota Notes

• YouTube Data API v3 free tier: 10,000 units/day
• playlistItems.list = 1 unit, videos.list = 1 unit, commentThreads.list = 1 unit
• A channel with 100 videos uses ~104 units per full run
• yt-dlp has no official rate limit but add small delays between downloads

Error Handling

• Missing YOUTUBE_API_KEY → stop immediately with instructions
• Missing yt-dlp → stop immediately with install instructions
• Individual video transcript failure → log warning, continue pipeline
• Comments disabled (403) → return empty array, continue
• API quota exceeded (403 with reason quotaExceeded) → stop and report progress so far