The guy says he doesn't know why they would shell a village across the border like that. I can see a reason why. The reason would be to prevent the Russian army from pulling troops out of that area and moving them into the Donbas area.
What I noticed in the two seconds before the girl stopped filming and started running to find mommy was that it was a tight pattern that indicates that the shots were well aimed, and aimed to hit an empty field and cause much concern, but not to damage villager houses, or to kill. The shell size was very small. Surprisingly small for a modern conflict.
I did some looking up and found that there are some old small D-44 85 mm guns in that area. The Ukrainians would have captured some of them from the Donbas separatists over the years because they are the old guns from storage that the Russians have been giving them since 2014.
They would just barely have the range to reach that village from the border, and only if they were placed right on the border. The small explosions I saw would be consistent with that approximately 3 inch size shell. Those were not shells from our big M777 155 mm (6 inch) guns, the 155 shells they use carry about four times that amount of explosive in the shell, and would have more than twice the range.
I would think that was a "shot over the bow" demonstration to the Russian using their own guns back at them to force them to keep those retreating troops there to defend their border, and not send them to the southeast where the Russians are being hard pressed to make headway. To send them where the Russians lost so many attempting that river crossing yesterday.
The Russians know that the Ukrainians have M777 155 mm guns in that area, if the Russians leave that border area undefended the Ukrainians could easily could set their big guns on the border and reach all the way into Belgorod which is a major logistical supply point for the Russians. With the rocket assist shells they have they could even reach beyond Belgorod.