The film organizes itself very quickly like this. Lots of little drops
drip down from the top of the loop. The film is still fairly thick; The
red/yellow part at the top is still small. All boundaries slowly move
down as the film gets thinner.
After a while, the yellowish part at the top has grown to almost half
of the area. Also at this stage, instabilities develop at the bottom:
slow waves start rolling along the stripes at the bottom.
At about the same time, fast instabilities form suddnely at the top,
and plunge down.
The top part has no color because it is thinner than 1/4 wavelength
of all the visible colors. It reflects all light and looks silvery.
Finally, swirls go all over the place and destroy all regularity
that there was in the beginning.
Several things go on at this stage that I don't understand: At the top of the loop, the film gets thinner and thinner. For a while top part reflects all colors and looks silvery or white. However above that a section develops that does not reflect any light at all, and you can look right through to the black paper behind it. Also, small (4mm) 'bubbles' of this black-looking stuff form at the very bottom and rapidly shoot upwards, until they merge with the transparent area at the top. As they move through the white section, they leave a thin black trail.