There are 9 photographs here stitched together.
They were taken with a Nikon D3 (borrowed - I sure as hell can't afford one of THOSE) in "continuous shooting" mode with a capture rate of 9 frames per second.
The entire process, from the ignition of the filament to those two tiny dying sparks you may not even have noticed at the very right end of the image, took exactly one second. In that one second, the human eye would have perceived a simple flash of light - a singular, static flash of no particular shape.
The human eye cannot see this, and yet you are seeing it.