There seems to be a book and web site called Socialnomics. On this site there is a graphic that looks at the first five years of Online Video. Below is a sample section.
I have mixed feeling about it. It leaves out a lot of people and a lot of the diverse content being produced. For example, how did the researchers define what is an education video?
In education video production there really is a wide range of people. Most folks who are producing online educational videos are not involved in K-12 or university level instruction. It can range from cooking videos, how-to do it, resource videos, hair care, green and sustainability videos and so much more. Don't get me started on the number of teens making tech videos.
Many of those folks would not define themselves as education content creators but that is exactly what they are doing. So that education category could be even larger than what is represented in the chart.
There is more to the graphic so you should check it out. Provokes questions that need more developed answers.