yt-dlp's days are fairly numbered as Google has a trump card they can eventually deploy: all content is gated behind DRM. IIRC the only reason YouTube content is not yet served exclusively through DRM is to maintain compatibility with older hardware like smart TVs.
Youtube already employs DRM on some of their videos (notably their free* commercial movies). if you try to take a screenshot, the frame is blacked out. this can be bypassed by applying a CSS blur effect of 0 pixels, permitting extraction; detection of DRM protection and applying the bypass is likely trivial for the kinds of people already writing scripts and programs utilizing yt-dlp. the css method of bypass has been widely disseminated for years (over a decade?), but programmers love puzzles, so a sequel to current DRM implementation seems justified. YT could also substantially annoy me by expiring their login cookies more frequently; I think I have to pull them from my workstation every month or two as-is? at some point, they could introduce enough fragility to my scripts where it's such a bother to maintain that I won't bother downloading/watching the 1-3 videos per day I am today -- but otoh, I've been working on a wasm/Rust mp4 demuxer and from-scratch WebGL2 renderer for video and I'm kind of attached to seeing it through (I've had project shelved for ~3 weeks after getting stuck on a video seek issue), so I might be willing to put a lot of effort into getting the videos as a point of personal pride.
the real pain in the butt in my present is Patreon because I can't be arsed to write something separate for it. as-is, I subscribe to people on Patreon and then never bother watching any of the exclusive content because it's too much work. some solutions like Ghost (providing an API for donor content access) get part of the way to a solution, but they are not themselves a video host, and I've never seen anyone use it.
> this can be bypassed by applying a CSS blur effect of 0 pixels, permitting extraction
That's not real DRM then. The real DRM is sending the content such that it flows down the protected media path (https://en.wikipedia.org/wiki/Protected_Media_Path) or equivalent. Userspace never sees decrypted plaintext content. The programmable part of the GPU never seen plaintext decrypted content. Applying some no-op blur filter would be pointless since anything doing the blur couldn't see the pixels. It's not something you can work around with clever CSS. To compromise it, you need to do an EoP into ordinarily non-programmable scanout of the GPU or find bad cryptography or a side channel that lets you get the private key that can decode the frames. Very hard.
Is this how YT works today? Not on every platform. Could it work this way? Definitely. The only thing stopping them is fear of breaking compatibility with a long tail of legacy devices.
Something I've never understood about DRM is, if the content is ultimately played on my device, what stops me from reverse engineering their code to make an alternative client or downloader? Is it just making it harder to do so? Or is there a theoretical limit to reverse engineering that I'm not getting? Do they have hardware decryption keys in every monitor, inside the LCD controller chip?
in short and simple terms, those parasites colluded with hardware manufacturers and put a special chip in your computer and monitor that runs enslavement software
without opening it up physically there is no way to make it stop or get the raw stream before it's displayed
This. Some ways back I actually purchased bluray recording device only to learn that its firmware is deliberately crippled to accommodate someone's business model. There are people who do the unsung hero work, but those types of skills are not exactly common and a business asshole is a dime a dozen any century you want to pick.
Yes, the decryption happens in hardware. For your OS (and potential capturing software running on it) the place where you see the video is just an empty canvas on which the hardware renders the decrypted image.
All levels of Widevine are cracked, but only the software-exclusive vulnerabilities are publicly available. It's only used for valuable content though (netflix/disney+/primevideo), so it might still work out for YouTube as no one will want to waste a vulnerability on a Mr. Beast slop video.
The reason they have different levels is that the DRM pitchmen got tired of everyone making fun of their ineffective snake oil, so they tried to make a version that was harder to break at the cost of not supporting most devices.
Naturally that got broken too, and even worse, broken when it's only supported by a minority of devices and content, because the more devices and content it's used for the easier it is to break and the larger the incentive to do it.
If you tried to require that for all content then it would have to be supported by all devices, including the bargain bin e-waste with derelict security, and what do you expect to happen then?
I don’t have any personal links but know that there is a constant cat-and-mouse game of cracking Widevine devices for their L1 keyboxes and using them on high-value content (as mentioned).
That’s why a lot of low end Android devices often have problems playing DRMed content on the Web: their keyboxes got cracked open and leaked wide enough for piracy that they got revoked and downgraded down to L3.
