Feline I thought the Ukrainians were the good guys.
As to the content this is why these days artillery batteries rapidly fire four or five rounds from each howitzer and then move so that they aren't just sitting there when the counter-battery fire arrives.
Needless to say this also applies to tanks being used as ersatz artillery.
Looking at the video again. Those idiots are rolling both projectiles (presumably unfused) and powder casings (likewise presumably empty) down the hill. This may not have been counter battery fire at all it may just be they rolled a projectile down the hill which exploded.
They look like rag tag militia without experience or discipline. If ordnance was handled like that in the Canadian, US or British army The officer or NCO in charge would be called to court martial for negligence.