How useful is AV/ video for instruction?

Best practices in Screencasting:

http://libraryguides.oswego.edu/video

http://ants.wikifoundry.com/page/Best+Practices+in+Screencasting

Meredith Farkas says use videos for conceptual overviews, step by step screenshots for instructions/how-tos.

And then the whole mess of evidence about utility of videos including:

http://acrlog.org/2014/01/13/tales-of-the-undead-learning-theories-the-learning-pyramid/

The graph I saw like this:

But seems to be based on this work:

http://www.danielwillingham.com/daniel-willingham-science-and-education-blog/cone-of-learning-or-cone-of-shame