So start with writing blogs or reviews on Reddit or your own page. Putting the time and effort into scripting, recording and editing a Youtube video before you even have a grasp of the core underpinnings of the endeavor seems wasteful.

I get the feeling you want to be a Youtube movie reviewer more than you want to review movies.

Serious question: If you don't have practice and experience analyzing films why would you start a Youtube channel doing it? That's like making a woodworking channel if you've never used a saw.