this sort of stuff is so grim, as well as lazy.

would love to have tried it without signup.

So basically you're freeloading off of the works of others without compensating them in anyway for creating the content that your business model relies on?

Yep, sounds like an "AI" product to me.

You need to get licensing rights for all of the videos you're using. Some of the creators will probably be stoked to have their video featured and won't charge you anything. The rest will probably ask for money, and you'll either need to pony up or stop using their content. Note: this especially includes the many American university videos you're using; their licenses generally prohibit commercial use of the videos.