https://www.cnet.com/news/amazon-prime-video-channels-everything-you-need-to-know/

So is adding any of them worthwhile? How do they compare to standalone options like HBO Now? How does the selection compare to Roku channels? Where do other services like Netflix or Apple's new TV service fit in?

They're optional add-ons for Prime subscribers, for an additional monthly fee, that provide on-demand or live streaming access to TV shows, movies and other video content from a provider. Subscribers can access the content from all compatible Prime Video devices, including  via the Amazon Prime Video app on smart TVs and media streamers, Android and iOS phones and tablets, computers and Amazon's own Fire TV devices and Fire tablets.