The issue with videos, is that they can become obsolete as soon as a new version of the library is released. Add to that the fact that a library user should get used to reading. There won't be any video for documentation. And pausing every few second to compare if we have the same thing as on the video, and rewinding the video a few second if I miss something is something I find very annoying and counter-productive. In a tutorial, I can stop mid-way, come back later and read again, and everything is still easy to follow and continue.