When the Sun is about to touch the horizon, a sort of red false sun rises up to meet it. This is called an inferior mirage. While the atmospheric refraction is indeed splitting the sun into different colors like a prism, one needs the inferior mirage to amplify the effect so we can see it easily.
When I see the red false sun come up from the horizon to meet the setting sun, I can be pretty sure I'll see a green flash.
During the second half of the video, there are a couple bits of green that peel off from the top of the sun. That is caused by an inferior mirage too, I believe.
Oh, and I'm going to try to borrow better tripod to see if it would help reduce all the wind induced jiggling in the videos.