Fred,
I like your theory but not your reasoning. Or maybe its the other way around. : )
I can right click the little box, then properties, then paste the web address of the file into my browser and see the pic every time. This indicates to me that the hosting site is not restricting access, as the pic displays without any collateral advertising or other junk.
I think it has more to do with how the browser handles the command to embed the image.
Ron