This is a classic case of overengineering a solution to a nonexistent problem.
On YouTube, the video and the description are also linked. They exist on the same page always.
And even if the concern this solution is covering is what if the video is somehow shared without the description, away from YouTube, then the video could just as easily contain the description or URL or QR code pointing to the file.
The description is not big enough to hold practically any data. You would need to link to it from there.... at which point the two are no longer linked into existence. Links go down insanely often.
This works really well until it doesn't. I have seen so, so, so many videos have linked content in the description that links to sites which don't work anymore.
Wait so your expectation is that instead of Youtubers using URLs to link to websites, you would prefer and expect that they download and embed those websites into their videos for you? Like, a zip file of the whole site? For.... convenience?
Have you considered using archive.org or mirrors instead?
There are an infinite number of better solutions for this...
On YouTube, the video and the description are also linked. They exist on the same page always.
And even if the concern this solution is covering is what if the video is somehow shared without the description, away from YouTube, then the video could just as easily contain the description or URL or QR code pointing to the file.
This is a just horribly unusable QR code.