To explain step 6 in more detail: The part where you type 0.1-1.0 (+0.1) is a fancy way of telling webui to create a series of images, starting with one at 0.1 denoising (almost identical to the masked section, paying very little respect to the new text prompt) all the way to 1.0 (respecting only the new text prompt and ignoring the masked section entirely), in +0.1 increments (0.1, 0.2, 0.3, etc., up to 1.0).
You could change that +0.1 to +0.05 and get twice as many images, or to +0.01 to get 10 times as many. It's up to an agreement between you and your graphics card.
Also, this is a BE example because that's the most obvious thing to do with this sequence, but it's pretty obvious how creative use of prompts can modify other things instead. I'll leave that up to your imagination.
Looking through their Twitter, I wonder if they're still using Stable Diffusion to generate these. They have tweets from Early October of generations from it (and Waifu Diffusion.)