Here’s Professor Bruce Levine giving the W. Augustus Low Lecture at the University of Maryland Baltimore County in 2008. This is from his book, Confederate Emancipation, which in my view successfully refutes the myth of tens of thousands of black confederates.
The video’s description reads, “Dr. Bruce Levine from the University of Illinois, Urbana-Champaign presents the lecture “Confederate Emancipation” on May 7th, 2008. It probes the public debate that dominated politics in the South during the last six months of the war, the controversy whether to emancipate and arm slaves on behalf of the Confederacy. The lecture explores racial and pro-slavery ideology, the interaction of blacks and whites, among other things.”