I installed the plugin and tried "add image" to add a default image. I expected to be able to look through my images library in order to select one. Instead, A "cheating?" message pops up.
Then I tried the route of getting an image URL by doing an "Add Media" to an existing post and copying the image's url.
I paste the image's url into the Default Image plugin settings dialog and click to add the image.
Again, I get the "cheating?" message.
I uninstalled the plugin.