Quote from The Very End :

Normally I would agree, but I can assure you that no one got injured on any way of those balls. They make you fly violently, but the inpact does not hurt since it's somewhat just trasfering the energy from the ball to your body pretty smooth and bunchy, instead of, with a normal ball would just smack your head in.
Ofc, it might hurt a little, but what do you expect when you hit the ball with full force right into the wall and back into your face?

Some of the children bumped with their heads against a wall or fell head-first on the ground, though.

Yes, it is a bit funny but I don't think that none of children in the first video got injured.

Quote from zeugnimod :

Some of the children bumped with their heads against a wall or fell head-first on the ground, though.

Darwinism.