OK. Looks like many of you are speaking about what you "have heard." Let me demonstrate to you what I "actually saw."
Each night, I would look out our door from another mountain. The sparks were happening on Mount Phu Chong in the distance. Not sure how far but they were visible enough, I could see the flashes as deep glittery pinkish red sparks. The sparks shot out from one location in all directions in about equadistant from one another. All tossed out into a radius from their original position where they were once together. Then the sparks would roll back to the center where there first started out. They would shoot out again all at the same time. (See the picture of the fire cracker below for a simulation.)
Of course, there weren't that many sparks. Just about 5 or 6. They looked round in the distance and not too big. Not even like a tennis ball. Maybe just a bit bigger than a regular marble.
The sparks were not big enough to create any kind of ray or any kind of light for any one to walk in the dark on.
The elders said those were dab ntxaug hunting for foods and playing at night. No Hmong was capable of creating those sparks, not even during the war era. Some elders said those sparks have happened long before the war, too, and that's how they have come to be known as dab ntxaug already.
I didn't see just one group. I saw lots of different groups in different locations on Mount Phu Chong. The groups didn't all spark out at the same time. There were no houses or thatches where those sparks were coming out of. No roads.
Some scientific mind should go and investigate. Just be sure to take a long a shaman's sword with ya!!