Good documentary on this comes from 'Peoples Republic of Desire'.
Live-streaming is considerably more mainstream, advanced, and in many cases an actual industry in itself now, outside of the west:
https://www.youtube.com/watch?v=WWdg8d18Tfs
I remember reading a while back about some controversy that some of the female live-streamers were being reported to the IRS for unreported income, with the IRS sending audit notices to them.
I first came across the concept in the delightful book "Dr Tatiana's Sex Advice to All Creation", which covers the evolutionary biology of reproduction in the form of an advice column with letters from birds, insects, etc: https://www.amazon.com/Dr-Tatianas-Sex-Advice-Creation/dp/08...