In simple terms, authorization is the process of verifying what users have access to (after authenticating). This video assumes that you already have authentication set up and are ready to add authorization.
Authentication is the process of verifying if a user is who they say they are. After a user successfully authenticates, access JWTs are issued back to the application.
In our case of authorization, we are using the JWT (JSON web token) in our NodeJS / ExpressJS API calls, to verify the user has the correct access to the desired resource.