Only for commie, rock sucking libtards.
Large scale cotton production by slaves on plantations provided the capital for the industrial development of the country. Not just the capital, but the attendant development of finance, logistics, and engineering which was then applied to other types of manufacturing.
The heyday of American domination of the world cotton market only lasted from about 1830-60. Had this narrow window been missed, the US would have been a backwater that for the most part missed out on industrial development.
Without cotton textile production spawning economic development, there would have been little need for the waves of immigration in the late 19th Century. Thus, descendants of those immigrants can thank their presence here to the Africans’ much higher resistance to malaria.
Most descendants of those Southern slaveowners were already here, so, regardless of how things turned out, would not have languished in overcrowded cities in western Europe.
So, while this guy has it mostly wrong, he is correct about slavery.