Video Downloader - Download Videos with yt-dlp
Download videos, audio, or subtitles from YouTube, Bilibili, Twitter, and 1000+ other sites using yt-dlp.
When to Use
- User asks to download a video
- User asks to download or extract audio
- User asks to download subtitles
- User provides a video URL (YouTube, Bilibili, Twitter, etc.)
- User wants to specify video quality (720p, 1080p, etc.)
Prerequisites - Auto Install
IMPORTANT: Before any download, check and install dependencies automatically.
Step 0: Check and Install Dependencies
# Check if yt-dlp is installed, install if missing
if ! command -v yt-dlp &>/dev/null; then
echo "Installing yt-dlp..."
brew install yt-dlp
fi
# Check if ffmpeg is installed, install if missing
if ! command -v ffmpeg &>/dev/null; then
echo "Installing ffmpeg..."
brew install ffmpeg
fi
# Verify installation
yt-dlp --version && echo "yt-dlp: ready"
ffmpeg -version 2>&1 | head -1 && echo "ffmpeg: ready"Run this check every time before downloading. Install automatically without asking user.
Instructions for Agent
Step 1: Ensure Dependencies Installed
Run the prerequisite check above. If yt-dlp or ffmpeg is missing, install via brew install yt-dlp ffmpeg.
Step 2: Parse User Intent
Identify what the user wants:
| User Intent | Keywords |
|---|---|
| Video (default) | "download", "video" |
| Audio only | "audio", "mp3", "music", "extract audio" |
| Video + Subtitles | "with subtitles", "embed subtitles" |
| Subtitles only | "only subtitles", "subtitles only", "just subtitles" |
| Specific quality | "720p", "1080p", "4k", "best", "worst" |
Step 3: Build Command
Base command structure:
yt-dlp [OPTIONS] "URL"Common options by intent:
- Basic video download (best quality):
yt-dlp -o "%(title)s.%(ext)s" "URL"- Audio only (MP3):
yt-dlp -x --audio-format mp3 -o "%(title)s.%(ext)s" "URL"- Specific quality (e.g., 720p):
yt-dlp -f "bestvideo[height<=720]+bestaudio/best[height<=720]" -o "%(title)s.%(ext)s" "URL"- Video with embedded subtitles:
yt-dlp --write-subs --sub-lang en,zh-Hans,zh-Hant --embed-subs -o "%(title)s.%(ext)s" "URL"- Subtitles only (no video):
yt-dlp --write-subs --write-auto-subs --sub-lang en,zh-Hans,zh-Hant --skip-download -o "%(title)s" "URL"Step 4: Execute and Report
Run the command and report:
- File name and location
- File size (if available)
- Any warnings or errors
Command Reference
| Task | Command |
|---|---|
| Best quality video | yt-dlp "URL" |
| Audio (MP3) | yt-dlp -x --audio-format mp3 "URL" |
| Audio (M4A) | yt-dlp -x --audio-format m4a "URL" |
| 720p video | yt-dlp -f "bv[height<=720]+ba/b[height<=720]" "URL" |
| 1080p video | yt-dlp -f "bv[height<=1080]+ba/b[height<=1080]" "URL" |
| 4K video | yt-dlp -f "bv[height<=2160]+ba/b[height<=2160]" "URL" |
| With subtitles | yt-dlp --write-subs --embed-subs "URL" |
| Subtitles only | yt-dlp --write-subs --write-auto-subs --skip-download "URL" |
| List formats | yt-dlp -F "URL" |
| Playlist | yt-dlp -o "%(playlist_index)s-%(title)s.%(ext)s" "PLAYLIST_URL" |
Response Guidelines
- Always confirm what will be downloaded before starting
- Show download progress or final result
- Report the output file name and location
- If download fails, explain the error and suggest solutions
Error Handling
| Error | Solution |
|---|---|
yt-dlp: command not found | Auto-install: brew install yt-dlp |
ffmpeg not found | Auto-install: brew install ffmpeg |
Video unavailable | Check if URL is correct or video is region-locked |
Private video | Cannot download private videos without authentication |
Format not available | Use yt-dlp -F URL to list available formats |
No subtitles found | Try --write-auto-subs for auto-generated subtitles |
brew: command not found | Install Homebrew first: /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)" |