Can one stream go to several platforms?
Short answer
Not yet. Each stream goes live on one channel. On a paid plan you can run several streams, each on its own channel.
Today
Each stream goes live on one channel at a time. To be live in more than one place, create one stream per channel. A paid plan can run several streams at once, each with its own playlist.
Several streams, one account
All your streams live in one Studio, with one Media library, so you can reuse the same media across channels.