Watching the airliner satellite video I noticed that some of the clouds lit up during the flash. I found a better copy of the video here and took a screenshot of the frame with the flash, and a screenshot of the frame immediately after. Then I used a difference filter in Photoshop and boosted the brightness a little with the curves tool.
This helped me see that the two clouds on the left and the one cloud on the right have a kind of halo around them. This would match the case where they are closer to the camera than the flash, so the flash causes them to be backlit. (These three clouds are completely black in the difference image because they are blown out, and the difference between pure white and pure white is zero.)
To the lower left of the flash there is a front lit cloud, which implies it is farther from the camera than the flash. Parts of this cloud that are farther away are less illuminated by the flash.
Another cloud at the bottom right is not blown out, and there is no obvious halo, which implies that it is also farther away from the camera than the flash.
If this is a hoax, the artist cared enough to accurately simulate the details of how clouds at multiple altitudes would be illuminated by a flash of light. I would guess it is unlikely that this video is 2D VFX work, but this doesn’t rule out a full 3D VFX pipeline (which would have been useful to create the “alternate angle” thermal video).