There are no imaginary weapons, and there are no DEWs at disposal to attempt such an event. The videos showed someone coming up to the stones at night, and leaving---and showed what was clearly an explosion. You might as well imagine the Pixies did it.

I've seen photos of scenes at car fires where the car was essentially destroyed, but other objects "across the street" were untouched. Distance and draft can make the difference between scorch and unscorched. Now you've heard of it.

Dynamite is the most likely possibility, as it is the most commonly available explosive. The "investigation" into the event would have established what? That the explosive was a nitrated organic compound? Any fingerprints? Any footprints? The problem is that you are using too much imagination and not enough hard reason.