The Information has a piece up, The Case Against Video. The Information charges a decent amount for its services which are in text form, so of course there is some bias here insofar as this belief was probably preexistent.
But I happen to agree. It strikes me that video is relatively low density, and it often takes reading to be able to combine facts/concepts together to form something new. It can be done via video, but it ends up taking more time.
For most people video will be sufficient, just as for most people television news is sufficient. But real depth will require reading.