The green is present in the July video, as are the clouds... But July clouds do not reflect green anything. Same place, similar circumstances. So, in the August video, I am of the opinion that it is NOT clouds reflecting green light from below. What is left? 1. Skyglow? 2. Aurora? 3. An electronic color shift caused by 5000 ASA and a wide open lens running at the edge of its exposure curve? I've seen that happen on both Ektachrome film (which is why it was cooled, to extend the exposure curve) and on some chips in my personal photography.
The green I saw in the July video might have been part of a faint skyglow. It seemed to stay put near the horizon with whisps unrelated to cloud movement. But, then, I have only ever seen photos of skyglow. The August green sky had, for a short time (maybe an hour real time), organization, shape, and movement. It was the identical green to July's green. However, from the type of movement... like a descending curtain, it reminded me of the auroras I saw in the Pacific Northwest as a kid.
Here is my speculative answer:
FIRST CHOICE is 2. this is a very faint aurora not visible to the naked eye but in dark sky conditions, able to be photographed. An aurora of this type would not need a CME to produce it... but would take lesser stimulation... perhaps even moderate coronal emissions.
SECOND CHOICE is 1. The extreme exposure may have caused the camera to record strangely in low light... recording some green where there was none, or recording some radiation, heat, or light (all EMF) as green. I wish I could have seen your Aug 11 video, before processing.
Uhm, BTW, you achieved your artistic objectives... beautifully done!
John