This is a semi-detailed instructional video on how to use the NodeWebkit functions (writing files) along with the Browser Javascript execution function and canvas snapshot action to take screenshots and then automatically write them to the app's parent folder.
Capx file link is here (Dropbox), because if I need to updated it quickly then I can without having to re-upload it everywhere.
Note: please feel free to share the capx wherever and with whomever. :)