Agreed, I hate YouTube videos for instructional content. I can read much faster than the instructor can speak, I can ctrl+f, and webpages don't tend to pad their content to fill a 12-minute video for 10 seconds of actual content.
My only gripe is that the page's margins aren't a bit more narrow.
Just adjust the width of your browser window to whatever width you prefer and the text will follow. That is, after all, what a browser was supposed to do: show text. If you use Firefox you can also open the inspector and select a mobile view (the two-screen icon top-right in the inspector frame/window) but that is more work for the same effect.
I generally just use the built-in reader view, so it's not really that much hassle, it's just slightly more work. Plus, reader view gets rid of all of the styles on the page, which would be nice to avoid.
A long time ago I found most YouTube videos were still completely comprehensible in 1.5x to 2x speed, depending on the exact speaker, and have been watching them at that speed ever since. Not just education but entertainment.
On the other hand, the downside is that you get used to that speed, and listening to people talk in realtime feels abysmally slow. Others may also ask you to slow down more frequently.
I do that with audiobooks as well, and when I set it to 1x speed it feels like the person is speaking intentionally super slow to make fun of the listener, it's odd.
2x is a much better speed, but still, it's annoying to have to watch 6 minutes of video to get the single sentence you want.
The layout's been just like this since last century. It was an appreciated feature when we were all on dialup, and at the time I found readability to be no problem on a 17" CRT monitor (10.5" x 14") at 800x600 resolution.
I can confirm it doesn't translate well to a modern ultrawide monitor.
A lot of videos on Youtube have automatically generated transcripts available via a menu item in the three-dot menu. Once the transcript is opened, you can use your browser's search function to search it.
The problem is that (most) Youtube videos are not people reading a technical document. It is geared toward "speaking" meaning that a lot of information is not covered due to time constraints.
My only gripe is that the page's margins aren't a bit more narrow.