I agree. The fallacy in his reasoning is here: "Let’s choose the very first key (in alphabetical order): AAAAAAAAAA. When we encrypt our plaintext of ONETIMEPA

I agree. The fallacy in his reasoning is here: "Let’s choose the very first key (in alphabetical order): AAAAAAAAAA. When we encrypt our plaintext of ONETIMEPAD with this key, we end up with a ciphertext of… ONETIMEPAD. Oops." Yeah, so what? He knows the plaintext already. An attacker doesn't and as you point out, there's nothing in the key that provides any information about the plaintext.