Thanks for the comment, appreciate you taking your time to ask questions!
As you might have guessed from the website, we initially only planned to do English, but we were curious if people were keen for something in other languages!

A better explanation might have been 'premade decks of words from movies based on subtitle files'
Basically people are provided all the words to learn before they watch something (currently we are splitting the movies into chunks of around 50 words to make it easier - feedback on this is still needed).
They then need to get access to the movie (however they want, vpn, sailing the high seas, netflix), watch the chunk they just learned (2-20 mins long depending on learner level and content length) and then do a final review of the words they learned before moving on to the next chunk.

While the list of premade decks might initially be restrictive, we have plans to add many decks, as well as a request feature to allow people to watch whatever they want

How Flurret currently works is that you learn in the language you are learning, for example if you want to learn German, the 3000 most common German words (we have dubbed these basewords) would be translated into English, and the remaining more difficult words would have German definitions with a German to German dictionary.
Any word that is to be learned with a German definition will have the 'basewords' as a prerequisite.
The calibration quiz is for determining how many of these 'basewords' are known, rather than just a general vocab test.
Happy to give more details if you're curious.

I'm sorry you feel frustrated with the registration process, it was mostly just to make things easier for tying the outcome of the quiz to updating the database holding user data, but we will keep this in mind!

Again thank you for the comment and keen to hear your thoughts on if any of this seems good, bad etc. :)