I mean, Prime Video is still a bunch of microservices, it comes down to where you define the boundary between 'service and 'microservice'. That blogpost was specifically about "the Prime Video audio/video monitoring service". Eg it's a service/microservice for QA, not for all of Prime Video. I'm sure there are seperate services for billing, browsing, captioning, and streaming.

And although the author called it "moving from microservices to monolith" it's more about moving from serverless to more traditional compute.