Quick video showing you how to fix the mouse scroll direction when you're using a mouse (Bluetooth or USB) with the iPad.
It's annoying but if you change the scroll direction using this setting, it'll also affect the trackpad, which you might want scrolling the other way.. at the moment there's no way to fix that.
Hopefully we'll see that in a new version of iOS in the future. Reversing the scrolling direction for mouse makes total sense.