I realize I’m being a reply guy here, sorry.
I have recently put some work into improving my YouTube RSS feed approach.
The official YouTube feed resource works well for me.
YouTube's official feed only shows the first 30 or so items in any given playlist. If you're unlucky enough to subscribe to one of the 50% of playlists where the owner appends new videos to the end of the playlist, as opposed to prepending them to the beginning, the feed will never reflect that once it has enough items.
To fix this, I wrote my own feed processor using the YouTube Data API v3 client and Java. If you want to subscribe to the beginning of the playlist, pass or omit the
reverse=false query parameter, and to subscribe to the end, pass