What the author fails to understand is that merely consuming text is not the be-all-end-all of being an educated citizen. I am wary of trusting an author who is screaming from the rooftops about how the bad thing is coming, how the world sucks so much more now.
It's my opinion that writing is by far a more effective way to understand the world and the nuance in it. You could, theoretically, watch a video on YouTube, understand it, think about it, and then write out your thoughts and ideas and would be far more educated than someone merely reading a novel.
There is always a strange disconnect with egg head types where they fail to understand that information input is not the only way to become smart. And valuable information exists everywhere: a book, a blog entry, a podcast, a video, a movie, in the real world, etc. Thinking that text, which by the way is one of the most inefficient methods of information consumption, is the only way to be "smart" is incorrect. Critical thinking is what is desperately needed.
To be fair, author's point is more nuanced than "kids these days". He traces an evolution from: (i) an overly conservative but reality-based oral culture, to: (ii) a reality-detached and turbulent text-based culture, capable of envisioning our current technological era, back to (iii) another overly conservative oral culture. To me, the perceived threat seems to be how this second oral culture won't be based on direct experience of the real world, but on other people's (and AI's) interpretations of the former: taking the worst parts of both previous cultures (i.e. you can't think outside the box, and your box isn't even real).
There's a further argument being made here that being literate changes the way you'd interpret and understand a YouTube video as you absorbed that information.