For information, `playlist_index` is `NA` by default (if not a playlist item) :   ```sh  $ youtube-dl -o "{{%(playlist_index)s-%(title)s by %(uploader)s on %(upload_date)s in %(playlist)s.%(ext)s}}" https://www.youtube.com/watch\\?v\\=QkeOAcj8Y5k  [download] Destination: {{NA-THE FASTEST WAY TO LEARN HOW TO OLLIE TUTORIAL by Braille Skateboarding on 20140802 in NA.mp4}}   ```