Mainstream streaming: where to watch online?
Currently you are able to watch "Mainstream" streaming on AMC Plus Apple TV Channel , AMC+, Philo, Sundance Now, MUBI, MUBI Amazon Channel. It is also possible to buy "Mainstream" on Amazon Video, Apple TV, Fandango At Home as download or rent it on Apple TV online.
You can also stream the title for free on Kanopy.