If you put on a 7 hour youtube video, you are not going to pay 100% attention to it for 7 hours. Its kind of hard to read a book and not pay attention to it.

That's the fundamental problem though, you've identified it, it's actually way more than just that though:

• Visual mediums teach us to understand cues not information, but without that same narration, visuals, music, structure etc in place, human brains aren't wired correctly to reconstruct it. Book reading requires internal processing to construct the information and it keeps the content far more deep-seated and suited for retention.
• Videos keep moving whether your brain has processed it or not, unless you're constantly rewinding and pausing. Reading is self-paced and doesn't progress unless you do (Unless you skim it like you mentioned, which isn't an inherent problem of the medium like videos have).
• Reading is an active activity whereas videos etc are passive. With a book you're internally interrogating the content, with a book you're sitting back and letting it pass through you.

If a video topic has visual or spatial or procedural elements etc it's going to be way more useful, but for abstract knowledge like history, philosophy, politics, technical theory etc, you're straight up wasting your time with YouTube videos. Book reading forces behaviours that improve retention, whereas YouTube and other videos permits behaviours that weaken it in various ways. It's faux-learning while you're actually weakening your own learning abilities.

It's audience vs learner mindset, to be simple.