From Speakeasy: Yup, It’s Him: A Pynchon Mystery Solved
"So is it possible to rule out the man in the “Inherent Vice” trailer as being the same guy in the Simpsons episode and German TV clip? Not at all, according to Primeau. In fact, he says, based on a preliminary analysis the speech pattern and inflection is “virtually identical” in all three clips."
The narrator of the BackToConstitution channel sounds a lot like Pynchon to me.
From: Smoking Dope with Thomas Pynchon: A Sixties Memoir: "The woman who brought us together once offered to arrange for Pynchon to speak in a university auditorium. She told him she could assure his anonymity by having him speak through a microphone from behind a screen. He refused: "They would still be able to recognize my voice." Ironically, that is exactly the situation of Pynchon's readers: he speaks to us from behind a screen, but we recognize him by his voice, that unmistakable Pynchon style."