No, not incorrect. Just a bit less clear. It sounds like "motn", but this often happens. I think it's an effect of the tone and the final consonant. You often hear it for this speaker and the word for "one".
It's wrong. It should not sound like "motn." He pronounces it correctly when it's not the first word in other sentences. This is a glitch or error.
Between "Hello, I am lost" and "A brave fish" which one do yout hink will be more useful if you find yourself in Vietnam?
To me it still sounds voiced, perhaps drifting towards slightly devoiced in the second half, something like [z͡z̥ʊ̌ˀŋ]. It doesn't sound like [s] to me.