The video on their landing page does a vastly better job explaining how it works:
I've got to say, that for meetings big/important enough where you've got someone dedicated to taking notes/minutes, this seems like it could be a really effective and compelling way of sharing meeting highlights/takeaways/fun bits with a broader audience, people who couldn't make it, or for posterity. A serious win for workplace culture and communication generally. (Of course, you never know until you actually try using it for a few weeks.)
But if this works well, hopefully Zoom buys them, and we'll expect to see Google and Microsoft build their own versions.