It's not complicated.
You need a path, the pen/hand/pointer layer and a background layer (picture, color, transparent) for the brush to work on.
Place the hand/pen layer in correct position, to the beginning of the path.
Use the "transition hand into whiteboard at start + transition hand out of whiteboard at end" if you want it to appear outside the image.
Or have the path beginning outside of your canvas, suits better for some animations.
Make sure you have the background layer active before running the plug-in.
That's it.
I recommend SaulGoode's old Combine/Overlay script and Tim's another plug-in Rename Layers for basic work afterwards.
Example, if you brush on transparent layer and want to make more complex background compositions, changing speed etc.
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PaintPathsinSteps.jpg [ 165.03 KiB | Viewed 4863 times ]
You can download the version 5 sample from GL to see how it works.
https://gimplearn.net/viewtopic.php?t=2419