If you are wondering how best to use the extension, our advice would be to do the following.
As a beginner, with every subtitle:
As an intermediate student, with every subtitle:
When you have reached an advanced level:
For all levels, if there's something tricky, or there's some new structure you don't really understand, don't get stuck on it for long. Keep moving through the subs. It's already quite helpful to be exposed the new structure, and be able to associate some meaning to it. If it's something important that you should learn, you'll see it again soon anyway, and you'll gain more knowledge about how it works.
You can also use a feature in the extension that greys-out infrequent words. A key to making fast progress in language learning is knowing what you can ignore, so you can focus on the really important words and structures.
Spend an hour or so working in this way every day, if you can. Your task is to 'digest' as much material as you can, and focus on listening. Use traditional language courses also, the Assimil, Linguaphone courses (original series), FSI courses etc. are very good. These provide a structured introduction to the grammar. Also try to find a conversation partner.
Here's a nice video which illustrates a good perspective for using the extension.There is a longer guide to language study here (written by one of the developers of LLN).
We hope you find our extension useful, and that you enjoy using it. Please feel free to contact us at LanguageLearningExtension@gmail.com
Best Regards, David and Ognjen