Funny thing is, this isn't even the tagging plugin we're supposed to be using- it's just that they haven't updated the one I ideally want for MyBB 1.8, and one that is similar requires PHP 5.4 or higher, and we're running PHP 5.3.something and when we tried upgrading it broke the image uploader links! Fun times all around.
I'll look into it and see if I can fix it myself...