Since this is old, I assume someone found these photos and then manually selected the pointer location. Maybe used openCV or something like that.. But I'd most likely go with manual.
Yeah probably. It likely made it significantly easier given that the images are always super zoomed in, so a single finger pointing covers roughly 6-8 mouse pointer locations (I'm kind of eye-balling it here).
There are 700+ images defined in https://pointerpointer.com/new-positions.json and the script finds the closest match to the current mouse pointer.