Vantablack is a pigment made from carbon that is so black that anything painted with it looks like a hole in reality. It absorbs 99.965% of visible light. The Action Lab Man made something even blacker than Vantablack, then shines lights and lasers onto it to see if it visibly reflects the light. He uses marks made with a black Sharpie and a paint called Black 2 (which absorbs 95% of visible light) to compare how well his black square absorbs light. There’s a surprising reveal at the end.