“Notice the 3 protruding jets at the base of the explosion.What is that?”
Several of those bombs were floated in tethered balloons at modest height. The jets are the steel mooring cables vaporizing, possibly with some secondary effects with streams of particles bombarding the metal vapor.
You saw similar effects on tower mounted devices with guy wires. The soft x-ray pulse traveled ahead of the fireball, vaporizing the wires. Dr. John Malik called it the “rope trick”.