How do youtube to mp3 converters work?

Question

YouTube

There are several online services where you enter a link, they give you to download audio from a vidos. How is it arranged under the hood? Do they pull all the videos from YouTube for themselves (they are not banned, is there an api or such a method)? Or pull from YouTube just audio? In the first case, in what language is the audio track extracted from the video?

Answer 1

There is a constant war going on, I get the titles (for downloading videos and converting), imitating the browser, first one then the second. On YouTube, they change tags so that they don’t cut out lines, just to spoil ...
If it’s money, then you can do it, otherwise there won’t be enough time.
I think these programs process the already downloaded video. When there is a stream, everything will stop working ... It seems to be. I don't know software.
Perhaps the scripts are somewhere, this is in the public domain.

Answer 2

How is it arranged under the hood?

youtube-dl

Or pull from YouTube just audio?

youtube-dl --audio-format
Why don't they ban and don't they ban, what to ask the project authors