I've written a script for Youtube-dl which scans the number of files in a folder then starts downloading from a playlist from that number so that it only downloads new songs from that playlist. The problem is that it starts downloading from the oldest songs. However when I use --playlist-reverse it ignores it and still downloads the oldest. This is what I have it as now:

youtube-dl --playlist-reverse --playlist-start `ls -1 | wc -l` -wic "URL of Soundcloud playlist"

I also understand that youtube-dl automatically doesn't re-download however it scans each file one by one. This becomes tedious when it has to scan 400+ files.