How Video streaming is implemented in popular online education websites

I need to build a web based video player. Something like coursera/udemy. I would like to know the following.

1. Where we can store videos (Blob,Db..etc)?
2. Say I uploaded video in Blob storage. How can I make sure nobody is able to download this videos?
3. What should be an ideal video streaming architecture(BE+FE) if I am expecting 500 concurrent users?
4. Do I really need to build a video streaming Back End or I can simply use services like vimeo to get this done?
5. I inspected how Udemy is doing, i could find the following. It looks like they are using some blob to store videos. But when I tried to access this directly it says I cannot. How this works?

Answer

There can be no way to protect your video from a determined sophisticated hacker. In the very worst case, they can record the video from their screen using a iPhone.

You can learn more about blob: URL e.g. here. The bottom line: it’s a browser-side object, it’s not to store videos.

You definitely can use streaming services, but this will even further reduce your control. OTOH, it’s not worth your effort to develop some new streaming architecture if you only expect 500 concurrent streams.