I didn't say documentation shouldn't be written; writing is just one of many media types.

Many people do not stay focused with longer formats in writing. So adopting a variety of media is a good idea, especially for the fuzzier "conceptual" documents, as opposed to reference documentation.

And I say this as someone who prefers books. I've made the mistake of only using writing, and noticed about half of the team just never seemed to grasp the concepts. Example projects with really short videos helped them a lot.