There's nothing factually incorrect about anything there. Oversimplified, yes. Overgeneralized, yes. But nothing actually incorrect.
Did some hippies follow bands that were into Eastern religions and maybe into Satan worship? Yes. There's no doubt about that. Heck, the Beatles released a few albums that were heavy on Eastern influences, and IIRC, George Harrison got very heavy into Eastern worship.
It doesn't mention the "normal" hippies that were part of a general counterculture that didn't really do anything except dress differently.
As for slavery, there were very few instances of slaves being beaten to death. DO NOT TAKE THIS THE WRONG WAY! I AM NOT DEFENDING THE PRACTICE OF HUMANS OWNING OTHER HUMANS! The landowner or plantation owner who had enough money to own slaves was not going to treat his slaves badly. The slaves ensured his profit from farming activity. Why would the owner abuse his slaves and hurt his bottom line? In many cases, and from doing research into my wife's ancestral roots, it seems like the upper middle classes would have hired hands as well as a few slaves that worked side by side in the fields. The difference being the hired hands could own/rent land, and the slaves were bound to the landowner. The horror stories seem to come from giant plantations with hundreds of slaves with multiple overseers, where the slave was like a cog in a wheel, and the plantation owner(s) had no real investment in the individual slave.
The real horror in slavery was the actual slave trade. There was no incentive for the ship captains to treat the slaves well on the passage. If anything, they had an incentive to overload the ships because they got paid based on live bodies at their destination port.
Same with the KKK. I watched a History Channel documentary of the KKK. The actual violence and murder was much more prevalent after WWII up through the 1960's. The early days of the KKK were exactly what the short blurb here says they were.