Download videos from your Watch Later playlist on YouTube

yt_download.sh

#!/bin/bash

# ==============================================================================
# Setup Instructions:
# 
# 1. Dependencies:
#    Install the required packages using Homebrew:
#    brew install yt-dlp ffmpeg
# 
# 2. Folder Structure:
#    This script expects to be run from inside a 'scripts' directory, which 
#    should be a subdirectory of your main video download folder.
#    
#    Example structure:
#    /Users/YourUser/Media/Videos/
#    ├── scripts/
#    │   ├── yt_download.sh
#    │   ├── archive.txt (will be created here by yt-dlp)
#    │   └── yt.log      (will be created here by the script)
#    └── <downloaded_video.mp4> (videos will be saved in the parent directory)
# 3. Browser:
#    We use Firefox because yt-dlp needs access to your browser cookies so it can
#    see the videos on your private playlist. If you use any Chrome based browser,
#    cron won't be able to get your cookies and the script will fail. Using Firefox
#    is the easiest way to circumvent this (be sure to open Firefox and log in to your
#    YouTube account).
# ==============================================================================

# Export the PATH so Cron can find Node.js, Python, and ffmpeg
export PATH="/opt/homebrew/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"

# Always run from the script's own directory so relative paths
# (yt.log, archive.txt, output path) resolve correctly under Cron
cd "$(dirname "$0")" || exit 1

# --- Lockfile mechanism (prevents concurrent runs) ---
LOCKDIR="$(dirname "$0")/.yt_download.lock"
STALE_THRESHOLD=7200  # 2 hours in seconds – auto-remove stale locks

# Remove stale lock (self-heal if a previous run crashed)
if [ -d "$LOCKDIR" ]; then
    lock_age=$(( $(date +%s) - $(stat -f %m "$LOCKDIR") ))
    if [ "$lock_age" -gt "$STALE_THRESHOLD" ]; then
        echo "$(date '+%Y-%m-%d %H:%M:%S') - Removing stale lock (age: ${lock_age}s)" >> yt.log
        rm -rf "$LOCKDIR"
    fi
fi

# Try to acquire lock (mkdir is atomic on all filesystems)
if ! mkdir "$LOCKDIR" 2>/dev/null; then
    echo "$(date '+%Y-%m-%d %H:%M:%S') - Another instance is already running, exiting." >> yt.log
    exit 0
fi

# Ensure lock is released on exit (normal, error, or signal)
trap 'rm -rf "$LOCKDIR"' EXIT INT TERM HUP
# --- End lockfile mechanism ---

# Path to yt-dlp (Use absolute path just to be safe for Cron)
YTDLP="/opt/homebrew/bin/yt-dlp"

# Check if yt-dlp exists there, otherwise try standard path
if [ ! -f "$YTDLP" ]; then
    YTDLP="/usr/local/bin/yt-dlp"
fi

LOGFILE="yt.log"
TIMESTAMP="$(date '+%Y-%m-%d %H:%M:%S')"

echo "" >> "$LOGFILE"
echo "=== Run started: $TIMESTAMP ===" >> "$LOGFILE"

$YTDLP --cookies-from-browser firefox \
  --download-archive archive.txt \
  --merge-output-format mp4 \
  -f "bestvideo[vcodec^=avc1]+bestaudio[acodec^=mp4a]/best[ext=mp4]/best" \
  --embed-thumbnail \
  --embed-metadata \
  --sub-langs "en.*" \
  --convert-subs srt \
  --embed-subs \
  --newline \
  --progress \
  --print before_dl:"%(id)s: %(title)s" \
  -o "../$(date +%Y%m%d) - %(title)s.%(ext)s" \
  "https://www.youtube.com/playlist?list=WL" 2>&1 | awk 'BEGIN { last_bucket = -1 } {
    if ($0 ~ /\[download\]/ && $0 ~ /[0-9]%/) {
      for (i=1; i<=NF; i++) {
        if ($i ~ /[0-9]%$/ || $i ~ /[0-9]%[^a-zA-Z]/) {
          val = $i
          gsub(/%/, "", val)
          pct = val + 0
          if (pct < last_pct) last_bucket = -1
          last_pct = pct
          bucket = int(pct / 10)
          if (bucket > last_bucket) {
            last_bucket = bucket
            print; fflush()
          }
          break
        }
      }
    } else {
      print; fflush()
    }
  }' >> "$LOGFILE"
EXIT_CODE=${PIPESTATUS[0]}

if [ $EXIT_CODE -ne 0 ]; then
    echo "$(date '+%Y-%m-%d %H:%M:%S') - ERROR: yt-dlp exited with code $EXIT_CODE" >> "$LOGFILE"
fi

echo "=== Run finished: $(date '+%Y-%m-%d %H:%M:%S') (exit code: $EXIT_CODE) ===" >> "$LOGFILE"

This is the cron command:

*/10 9-20 * * * /Users/YourUser/Path/To/scripts/yt_download.sh

Adjust the absolute path to where your script is. If unsure, run pwd in the same folder and append the script name.

To setup the cron job, run crontab -e, edit the file with the line above, save, and exit.