If you would like to know more, here's a daily mail article for the event. It appears this may have been a black mother (does not appear to be so), but it does have this gem from the mother of individual that flying-kicked the child:

He didn't try to kick that baby, he tried to jump over the baby on to her and made a mistake. My kid is not the type to kick a baby, accidents happen.

It also seems the mother being attacked may have been pregnant.