Strange, it seems to be technically working but not the way you showed us. This is my before and after of welding the verts when I toggle your script, it's not stitching the verts on the fingers together like it does for you for some reason, not sure why.
Great thanks! I was able to install it and assign it to a hotkey and put it in my toolbar. However when I'm in my UV editor and I select two or more verts and then run the toggle for the script nothing happens. Am I using this wrong?