What is Satan's underlying goal according to the video?
Satan's underlying goal is to usurp the throne of God religiously. At Babel, people in rebellion built a religious center to replace God's instructions with what Satan would promote himself, attempting to take God's place. This has always been Satan's goal.
Les explains that after Noah's sons came out of the ark, they repopulated the Middle East for 200 years, then in total rebellion against God's instruction to scatter, they gathered at the tower of Babel under Nimrod. The tower was not intended to take brick and stone all the way to heaven; it was a place of religion whereby they could literally usurp the throne of God religiously. Les teaches that this has always been Satan's goal. They were going to replace the things God had instructed with the things Satan is going to promote himself.