Problems under working in a company

If you work for someone else with your talent, then you will lose your valuable time and money. 

Corporate world can give you money but not for a long duration of time. 

Why a teacher or an instructor shouldn't make videos under other people or a company?

You will be less paid. They will reap the benefits from your videos. Simply because they are a big company and have money at the moment. 

If you have a skill in the digital age, don't waste it working under someone else. 

First check where do you find most people? 

Most people today are on the internet. Mostly in social medias and the various blogs or websites. Lets consider YouTube also as a social media. 

Just you need to create videos and publish them for free. Once a strong customer base is made then you can offer your paid service. 

You can sell your full tutorial videos to them. There are a number of platforms that allow you to sell your videos where the customer can gain access only after purchasing your course. 

Once you have a video course try posting it on various platforms and earn money.