Bravo for this demo, Jodi. You've inspired me to do my own.
I followed the link to WCAG, very interesting. But, in my opinion, the image + alt text example is curiously not very relevant. According to the site, the best alt text should be: "A distraught man hugs his daughter in front of the crumbling walls and scattered debris of their home destroyed by a tornado". I didn't SEE it was a father and daughter, I can't SEE it. I didn't see that it was after a tornado, I didn't see that it was a tornado, I can't see it (it could have been an earthquake, a bombing, destruction for eviction, etc). So, in this example, there's a lot more information (contextual and especially emotional) in the alt text than in the image. Is it a good alt text? Does anyone have an opinion?