Suppose there is a playlist in youtube and you want to download videos indexed at 7 to 9(the indexing starts at 1),the command should be
pip -install youtube-dl
traverse to the directory in command line where you want to save the files
youtube-dl --playlist-start=7 --playlist-end=9 -ci
https://www.youtube.com/playlist?list=PLQVvvaa0QuDc2QjQOkZ4rtLYZVll_sZFZ