Being a different medium does in fact make it much better for wasting time. Skipping a paragraph in a book takes 100 milliseconds. Referring back to a previous paragraph to understand a seeming contradiction does too. Pausing a book requires no effort, and no effort to return to the place where you were. Books can be excerpted and quoted, not just in other books, but also in conversation or in videos, in a way that videos just can't. (Talking-head filler scripts can be quoted that way, but the video can only be quoted in video or still images.) Errata sheets, errata websites, and later editions of books can correct errors in earlier editions. Books are much smaller and therefore easier to archive than videos, making them less likely to get lost.
Neil Postman's Amusing Ourselves To Death is an extended and very persuasive reflection on precisely this difference in the tendencies of these two media, although particularly attuned to the form of video that was popular at the time, TV, which had commercials and didn't even have pause and rewind.
somehow I doubt that the person I was replying to would consider ebooks as a book.
videos can be viewed in double speed, and they can be rewound. they can be watched over and over if needed. they can describe/demonstrate information in ways that books can only project into 2 dimensions. a picture is worth a thousand words - well imagine 24 of those per second.
certainly with STEM subjects, nothing beats a good animation.
even for things like history/geography, I find animations and progressive disclosure to be much more engaging and easier to remember than dry words on a page.
Neil Postman's Amusing Ourselves To Death is an extended and very persuasive reflection on precisely this difference in the tendencies of these two media, although particularly attuned to the form of video that was popular at the time, TV, which had commercials and didn't even have pause and rewind.