How to make facebook video downloader?

how to make a facebook video downloader? using API or any other method

Search in Google and you will find tons of APIs for this. Most of them are paid, the free version will be only a few daily downloads. But you can use 4 or 5 different services in your app to be able to provide hundreds of daily downloads to your users. But if your app have lots of users then you better create your own solution or use a paid API.

How to do with an API… like from rapid API…
Can you share blocks please …

The API documentation will show you how to do it. If you want to hire me to do it for you, PM me. Otherwise, try it yourself and if you get stuck at some point then you post in community and I and others can try to help you.