Here's the plan for the livestream.
I will host it on my programming channel on YouTube.
It'll be primarily a broadcast of the Discord room, and I'll try to provide some live demo of the features and extensions discussed whenever things are voice-only. And if there's anything you'd like to see demoed in real time, just ask in the chat during the stream!
The stream is scheduled on YouTube so you can set a reminder if you want. It'll be also available for replay later, as well as rewindable if anyone joins late and wants to catch up.
I'll go live about 10-15 minutes in advance, so that everything is ready when the rest of the Flarum team joins on Discord. As for how long it will last, that'll depend how things go on Discord! If there's still an audience when the team is done, I can do some additional demos or discuss some developer aspects.