YouTube-dl has an interpreter for a subset of JavaScript in 870 lines of Python

Google attempting zero days on client computers would be something. It's not totally without precedent (Sony CD rootkits - https://en.wikipedia.org/wiki/Sony_BMG_copy_protection_rootk...) but would still be major news.

This is the compiler writer equivalent of parsing HTML with regex:

It is technically wrong - it isn't a sufficiently rich and powerful approach to handle all JS (HTML) that you might throw at it. It'll work for a while until it eventually barfs when you least expect it.

EXCEPT that if the inputs you are giving it come from some understood source(s) that aren't likely to change, then a simpler approach to the "all singing all dancing" correct may be appropriate and justified. E.g. because it might be easier to write, easier to maintain and/or less attack surface etc.

youtube-dl targets a lot of websites other than Google properties, many of which are a lot sketchier (think, uh, NSFW streaming sites).

The goal of youtube-dl is to download a video off of YouTube for offline storage.

This isn't something YouTube particularly enjoys. They would rather you keep coming back -- every visit is more ad revenue for them. If you have an offline copy, you don't need to visit YouTube anymore.

YouTube has an incentive, therefore, to make it more difficult to download (or "scrape") their content.

I'm not particularly sure of the specific details, but apparently YouTube has added JavaScript (a programming language that executes in the browser) as a hurdle to jump over. A simple python script doesn't have enough brains to execute JavaScript, only enough to realize that it exists. (Clearly, youtube-dl is sophistication enough to have jumped over it.)

These are the conclusions I come to, having written software for about a decade.

1) Once you give information to someone, be it text, pictures, sound, or video -- they will do whatever they want with it, and you have no control. Oh, yes -- it may be illegal. Maybe unethical. But the fact of the matter is you do not have control over information once it leaves your hands.

2) Adding hurdles to make it harder to access the information does little to stop someone who is dedicated to accessing it.

3) Implementing a subset of JavaScript in such an elegant and tiny manner is quite impressive.

How you interpret these facts depends on your worldviews. If you are a media and content creator, you will view these facts differently than a politician, and a teenager.

As an engineer and amateur philosopher, I certainly support the rights of content creators to be paid for their work. And yet, I fear that more and more, content creators want to lease me a right to listen their music, instead of own a copy of it.

I used to own CDs, DVDs, movies, and books. What happens if Amazon or YouTube decides to not serve me anymore? Anything I've "purchased" from them, I lose access to.

Further more, if I create a song, I used to be able to burn copies of CDs and distribute it on the street corners. Now, you have to sign up to stream on Spotify. This is a double edged sword -- I get a wide audience, but Spotify will do whatever they want with me.

This troubles me.

One of the reasons people use yt-dlp/youtube-dl (and nitter.net/etc) is to transform the modern proprietary JavaScript web into something more suitable for enthusiasts of the old document web and of FOSS. If the web switched to plain then yt-dlp/youtube-dl would become completely unnecessary. Your browser should not have to run JS to watch an embedded video.