Got "invalid login attempt" after creating account and validating email. Once I'm logged in maybe I can give some more based feedback.
A priori, sounds good, solid idea and I don't think anyone can doubt that video based immersion is part of a healthy language learning diet. Question is, can it be the main course?
I've had a pretty similar path of learning English as yours so my main doubt is the following: I don't believe that the experience of a video game is the same as that of a video with social/cultural significance (those come usually only in your native language and in English) which are both quite different from "some" video on youtube. So it's a question of level of engagement with the content.
Having said that, I would like to see what other supporting structure you have / will put into place. Codifying vocabulary and grammar as well as written and oral practice will somehow need to be tackled in a "one-stop-shop" application.
https://www.youtube.com/watch?v=mfv0V1SxbNA