Even audio books, the authors point out, are not the equivalent of reading but a poor substitute for it.
I'd love to see the data that they have to backup this claim. I remember reading a while back that listening to an audiobook gets all the same mental benefits of reading a book, as long as you are reading above a 5th grade level (basically sounding out words).
Was that for reading for enjoyment or for information. In my experience I find folks who prefer written documentation over video explanations tend to figure out and perform things better. I also find those who mostly get their information from videos have a hard time understanding and doing due diligence on sources and thus tend to get emotional over things that are not entirely true or presented in a very slanted light. While you can rewind to double check something said before in a video I find few people, including myself (and I likely do do it more than most) will bother to rewind and do the double check. When reading its much easier to page back and check that item. Its also way easier to assess data from multiple sources and you can chekc particular parts of writings within minutes easily wereas finding and checking areas of videos where they all talked about the same thing is not so easily. Even scrolling around a forum or search for things is easier. Heck searching to get text is much more likely to quickly find you something than search video for a specific thing.
It was in reference to reading for enjoyment. There's definitely a huge benefit to having written documentation to search through for technical purposes for sure.