Definitely a service business in my view:
Alternatively, a business is a service organization if capital is not a material income-producing factor. [BL 130] Whether or not capital is a material income producing factor is decided on the basis of all facts and circumstances. The regulations give three examples to illustrate this point:
Capital is a material income-producing factor for banks and similar institutions.
Capital is a material income-producing factor if there is substantial investment in inventories, equipment, plant, and machinery.
Capital is not a material income-producing factor if the income of the business comes primarily from fees or commissions for personal services performed by one or more individuals. [Prop. Treas. Reg. §1.414(m)-2(f)(1)]
Given this definition, most all manufacturers, retailers, and wholesalers will not be service organizations, because capital is a material income-producing factor in their business. [BL 76; BL 77]
Seems to me they clearly do not have capital as a material income producing factor; income come primarily from fees for the videos (personal services of teaching). FWIW.