Preachers and Biblical commentators who posit the Sons of Seth theory are the knuckle-draggers.
God didn't bring the Flood because man was evil (or he would have done it again and again and again). He brought it to rid the Earth of what was alluded to above and in your video.
I have always believed that to be 100% true. We do not serve a homicidal God. Well stated.
Consult Genesis 6:5-7
"5 The Lord saw that the wickedness of man was great in the earth, and that every intention of the thoughts of his heart was only evil continually. 6 And the Lord regretted that he had made man on the earth, and it grieved him to his heart. 7 So the Lord said, I will blot out man whom I have created from the face of the land, man and animals and creeping things and birds of the heavens, for I am sorry that I have made them."
God is patient, and administers justice in His own time.
Romans 9:22-24
"What if God, although willing to demonstrate His wrath and to make His power known, endured with much patience vessels of wrath prepared for destruction? And He did so to make known the riches of His glory upon vessels of mercy, which He prepared beforehand for glory, even us, whom He also called, not from among Jews only, but also from among Gentiles."
FReegards!