When I watch these videos and I think about people treating other people so cruelly, I can't help but think that the root cause comes from insecurity. Insecurity breeds fear of "other", desire to have power over "other", a desire to feel better than the "other". I think a feeling of insecurity often starts infancy. I think some answers can be found in Erikson's Psychosocial Stages, Siegel's Attachment Parenting and Adler's feelings of inferiority resulting in a superiority complex, when the feeling of equality is what is healthiest for all.
So how can we address the systemic cause of racism and cruelty toward others? What about putting tons of money into supporting pregnant parents? Help them establish social cohort networks of other parents at the same stage of pregnancy. Support them with the material things that new parents need, have support groups that provide childcare and have dinner served with guest speakers that can share developmental information, attachment parenting concepts, compassionate communication, helping people come to terms with the good and bad of their parents approach with them and come up with a cohesive narrative of their own upbringing. "Graduates" can become one on one mentors. It could just become part of prenatal care in our country, based out of hospitals and birth centers.
Key to preventing future violence and cruelty would be to get parents to reject spanking and all other forms of physical punishment. Physical punishment sends an early message that "might makes right", that you can act out your frustration by being physically violent to another person, that older/bigger/stronger individuals have the right to inflict pain, that you can legitimately communicate a message with violence; but it creates a confusing dissonance of "this person loves me, protects me from harm, but then inflicts harm on me." Some people say "Oh I don't spank in anger". Truthfully, I think inflicting pain when calm is perhaps even more disruptive to the psyche. The ability to dole out physical pain with an absolute lack of empathy sets a disturbing precedent. That could be the basis for a cop putting his knee on the neck of another person. And just the use of physical punishment can be why people find themselves trapped in physically abusive relationships as either a victim or victimizer.
Of course bringing each community in our country to a proper level of functioning is key. All children should have have well funded schools (starting in preschool), opportunities for recreation and enrichment, teen volunteer and employment opportunities, healthy food, clean water, fair wages for parents, quality and affordable child care, safe homes, and beautiful park and natural areas. When a person feels cared for, secure, and safe they are much less likely to be cruel and more likely to feel empathy for others.