At one point he had to tell them, “It’s pronounced, ‘Doom-iss,’ you dumbass.”
I didn't watch the video to hear the alleged mispronunciation. However, for the French writer Alexander Dumas, if using the native French, then "Dumas" is pronounced "Doo-mah."
From wiki: "Alexandre Dumas (UK: /ˈdjuːmɑː, dʊˈmɑː/, US: /duːˈmɑː/; French: [alɛksɑ̃dʁ dymɑ]; born Dumas Davy de la Pailleterie ([dymɑ davi də la pajət(ə)ʁi]), 24 July 1802 – 5 December 1870),[1][2] also known as Alexandre Dumas père,[note 1] was a French novelist and playwright. "
Or did I miss something here?