Because the shutter was so slow, I had it stopped way down, with a fairly low ISO. It really came out to be I think four separate exposures, because there was nothing much being recorded without some light.
Notice the big bolt on the right, down below it, there's a cloud. You can see the movement of the cloud between flashes.
I think a really great use of that feature on your K3II would be to reduce noise with shots taken at high ISO in dark conditions.