The plain text material I post using cut and past, and usually blockquote with newlines and paragraph separators to math the original.
For screen shots, well, they are just screen shots.
Some images, like the two from the airplane window, I download JUST THE IMAGE, transport it to a posting site, and then provide those URLs (I usually assign the image name, but did not with AF1_5* images.
Most of my posts include some HTML code, and if one puts in a single piece of that, then ALL has to be HTML formatted.
If you cut and paste plain text, and there is no HTML code in it (which is typical), then FR will render it the same as your cut and paste.
Thanks, I should just go there.