Since most anime episodes are about 20 minutes long, watching it twice in a row will take about 40 minutes in total. Make sure you pick a good one, since you don’t want to get board on that “Japanese only” replay. Also, all of this is going to be harder if you’re just starting out with Japanese.
You will want to study and learn those words on your own so that you brain knows that these new words are important to you. In other words, your brain will know what to look for (listen for?).
Babies literally take years to learn a language this way. And a lot of times people talk to them in short, simple sentences. Plus, babies tend to participate with the language more than most people who passively listen to it.
It’s a pretty cool feeling when you’re watching anime and you actually comprehend what the characters are saying for the first time! It’s also super motivating!
This is a system that deletes, distorts, and generalizes all of the non-important information that you take in.
You first study them in isolation, that is, not while watching anime. And then you watch the anime afterwords to hear the words that you studied in action.
They are able to fully hear the different sounds of each language and there is very little crossover. How this applies to Japanese with anime is that when you are watching it, your brain is going to ignore the Japanese sounds that you’re not used to hearing.