You can download videos and playlists on YouTube with this script. Script has GUI. Enjoy.

git clone https://github.com/GhstRt/Youtube-Video-Playlist-Downloader-PyQt5.git

pip install -r requirements.txt

Download FFMPEG on "https://github.com/BtbN/FFmpeg-Builds/releases" and add path /Your Directory/ffmpeg/bin

Run mp3-mp4.py with Python3

Licenced with GNU General Public License version 3 (GNU GPL v3).