Some commands which you may find useful while downloading a playlist
Download a playlist
youtube-dl <playlist link>
Best quality video and best quality audio (merged ) + preferred resolution
youtube-dl -f 'bestvideo[height<=1080]+bestaudio/best[height<=1080]' <playlist link>
This command will download videos in 1080p resolution if 1080p is available otherwise it will download the next best (less than 1080p) resolution. Here, You can use 480 or 720, etc instead of 1080.
Note: Make sure that ‘FFmpeg’ is installed, otherwise video and audio will not be merged.
Best quality video and best quality audio (merged ) + preferred resolution + Add video upload date on the file name
youtube-dl -o "[%(upload_date)s] %(title)s.%(ext)s" -f 'bestvideo[height<=1080]+bestaudio/best[height<=1080]' <playlist link>
Best quality video and best quality audio (merged ) + Preferred resolution + Add video upload date on the file name + Add uploader name on the file name
youtube-dl -o "[%(upload_date)s] %(title)s [%(uploader)s].%(ext)s" -f 'bestvideo[height<=1080]+bestaudio/best[height<=1080]' <playlist link>
Subtitle
Best quality video and best quality audio (merged ) + Preferred resolution + Download auto-generated Subtitle
youtube-dl --write-auto-sub -f 'bestvideo[height<=1080]+bestaudio/best[height<=1080]' <playlist link>
Best quality video and best quality audio (merged ) + Preferred resolution + Download video creator’s uploaded subtitle
youtube-dl --write-sub -f 'bestvideo[height<=1080]+bestaudio/best[height<=1080]' <playlist link>
Best quality video and best quality audio merged + Preferred resolution + Download video Creator’s uploaded specific language’s subtitle
youtube-dl --write-sub --sub-lang en -f 'bestvideo[height<=1080]+bestaudio/best[height<=1080]' <playlist link>