I tried "He lives in this quarter" and got told the correct answer was "He lives in this burrough"!!!
("burrough" is a very odd, perhaps archaic spelling of "borough", and even that's an odd phrasing.)
No, it is like the "dd" in American English "buddy," an alveolar flap/tap in IPA.
That's what I meant! Is the m/n thing right? Sounds more like an m than n to me.
Great. Not only am I crap at languages, I've also got hearing problems.
Not at all. The «n» in Portuguese is pronounced slightly differently than the English "n." In Portuguese, it is denti-alveolar (pronounced with the tongue closer to the top of the teeth/gumline), while in English it is completely alveolar (on the alveolar ridge behind your gumline in front of your soft palate above your tongue). Plus, the audio is a bit fast, especially for learners.