In some dialects (Connemara Theas), it is pronounced as nú instead of nó. Generally, nó is correct (roughly) as you said. However, know that the speaker doesn't consistently speak one dialect, and usually doesn't speak with actual Irish.
Unless you're a native speaker, you likely don't speak any dialect. And there is no Leinster Irish -- the last native speaker of Offlay Irish died in the 1960s. So you likely speak "Learner's Irish" unless you've put an effort into learning a dialect.