When using the Options "Remember last playlist" and "Remember File position", opening MPC-HC and clicking play will resume playing the file that was last open at the last position within the playlist.
If the video that is playing within the playlist when MPC-HC quits is a youtube url (and presumably any other site supported by yt-dlp), when MPC-HC is restarted instead of the youtube video playing, the playlist restarts from the first video.
When using the Options "Remember last playlist" and "Remember File position", opening MPC-HC and clicking play will resume playing the file that was last open at the last position within the playlist.
If the video that is playing within the playlist when MPC-HC quits is a youtube url (and presumably any other site supported by yt-dlp), when MPC-HC is restarted instead of the youtube video playing, the playlist restarts from the first video.