Welcome to GoFastNews Larry.
Thanks for sharing you thoughts on the interesting video.
Here's a link to a higher quality version of the same video with a frame counter:
Schlieren Imaging
Early flame development is determined by large scale in-cylinder flow, in this
example the mixture at the plug is very quiescent, thats just a fancy word
the educated use for still or inactive. I suppose this was staged to
photograph laminar burning which is much more organized than turbulent
flame. Perhaps squish was left out for the same reason.
With no movement to stretch the flame kernel, the result is flame kernel
development in the vincenty of the spark plug. If swirl were present the
flame kernel would stretch in the direction of the flow developing a larger
flame area during the early stages and faster transition to turbulent flame.
The earliest frame I'm able to capture is 83, showing what you describe.
Two things I would like to point out. First the flame develops faster on the
left side of the chamber, the the early flame kernel that shoots to the top of
the cylinder results in development on the left side a a rate over 2X the
right side. My thinking is the ground electrode cools the flame kernel
delaying development in the area.
Secondly watch just below the spark plug when the flame front reaches
the activity at the piston surface after frame 133, the flame explodes,
the difference between frame 133 and 175 is enormous. This I would think
is what is described as a wrinkled laminar flame front, the key to elevated
flame speed. Your thoughts?
.