I was able to set the order to descending by editing the “Playlist settings” on the Youtube playlist page (for example, https://www.youtube.com/playlist?list=PLbH1P6VftyvXaSRf3NpUNuCSTWpPER7tD). The order settings that are included with the plugin don’t do anything, so they should probably be removed and instructions added to edit the order on the Youtube playlist page.
Here’s an example of a gallery displaying in ascending order even though the settings are set to descending order: http://www.vintagegrace.org/watch-sermons/
