1. Your base page doesn't describe what topics can or would be available. What are we trying to learn here? Languages? Science? How to be a better YouTuber? 2. You have a demo video. I haven't watched it. Why? Because I HATE having to watch videos if I could read a description instead. I read at least 10x faster than I can watch anything. That applies to learning as well, but some topics do work better in a visual medium. 3. You say its free but requiring me to sign up. To me that's not free. Maybe its not needing my money, but you're still needing my information. 4. Offer sign up/sign in with other identity providers.
TL;DR - Spend some time describing your product to someone who doesn't know need your product, not explaining it like I've tried other products and need shortcuts.