Yesterday this position was also under heavy fire.
Today it even comes closer.
Another longer video can be found here:
Some of the fire (especially when it is at an exact same location) comes from the Ukrainan artillery:
@BBCDanielS the quick silent big flashes is artillery firing.Ukr army artillery fired at least 11 times in that video pic.twitter.com/idbqOiTHtQThis is the damage done by this shelling:
— Crimea&East (@IndependentKrym) 20 mei 2014
Dmitry Tymchuk reports there were 4 soldiers wounded in this attack.
Also see: Ukrainian army is not in control of Slovyansk at all