> How will showing people short video clips to create a drug like drip of enjoyable chemical reactions in the brain progress the species?

Possibly (pure speculation here): if you carefully observe, at massive scale, how a system [1] behaves, it may provide some insights into how it is implemented. And based on those learnings, iteratively improve how the platform feeds tests and analyzes responses to gain deeper understanding of the system over time.

[1] In this case, "the system" consists of individual human minds, as well as the overall network of minds.