This fix I'm afraid has a few limitations, well one limitation really and that's that it will only work on the Google Chrome browser. Not too much of an inconvenience Chrome is a great browser and can be quickly downloaded.
How To Invert A YouTube Playlist
1. Follow this link to the Reverse YouTube Playlist Page in the Chrome Store.
2. Click the download button in the top right to install.
3. Now when you open a playlist in YouTube you will see two arrows in the top right beside the autoplay and random buttons.Click the arrows to reverse the order.
A great add-on for Chrome although it is a pity YouTube have not built in this option for this especially with all auto populated playlists playing from back to front.Let us know what you think in the comments.