This is an adapted excerpt from the Nov. 9 episode of “Velshi.” On Feb. 18, 1915, President Woodrow Wilson screened a film for senior government officials in the East Room of the White House. It was called “Birth of a Nation,” a three-hour piece of propaganda that glorified the Ku Klux Klan and portrayed emancipated Black Americans as unworthy of freedom. It marked a chilling inflection point in the U.S., when white nationalism stepped out of the relative shadows and into the center of government.