Much like adding a YouTube channel, you just need to find the correct list ID, and then plug it into this link:
http://gdata.youtube.com/feeds/api/playlists/PLAYLIST_ID

To find the playlist ID, navigate to the playlist on YouTube, and then look up at the URL at the top. You'll see something like this:
https://www.youtube.com/watch?v=b8DCN8Bf_Uk&list=PLyL0T6feQGOwJD_hPsXlLqrJN_7Ozg5ZB

The list ID is the long string of characters at the end after "list=" So just copy that ID code and paste it into the RSS feed link above. It will look like this:
http://gdata.youtube.com/feeds/api/playlists/PLyL0T6feQGOwJD_hPsXlLqrJN_7Ozg5ZB

Just paste that into the Video Feed URL slot in the Videos module of your app, and make sure to set it to YouTube.