This indeed is a Matteus skill and is from the Matt battle demo, which actually allows you to see Matteus skills in action using default Matt's skin.

Then, there's a silly bug which allows Matt to stand right in front of the foes instead of further back, iirc you do this by playing a skill animation when he's in the middle of another skill animation.

As for how Matt was knocked back, whoever recorded this simply timed the bomb's explosion to the click of a button that plays Matt being knocked back animation.

Not a player skill.

cringe, matteus uses it

I am gonna bet on removed, preatty sure I've never seen it before.

No clue this was taken in the demo testing stages of EBF5 in 2017 and I haven't played that game at all so chances are it was removed or it was for a boss fight

what skill is that?