It actually reminded me of the aftermath of an arc flash ( https://en.wikipedia.org/wiki/Arc_flash ) which while the original arc is visible (and may temporarily blind any that see it) the plasma that comes out after it is not and is extremely scary because it's potentially several times hotter than the surface of the sun. The linked article has a video in it that describes the results.

I was looking for a comment that mentioned this! Pit crew methanol fire is also what I first thought this article was about when I read the title!

Alcohol fires in general, for that matter - ethanol fires are also just about invisible.