You can’t. What I usually do is create a new topic and add that featured topic to the event. We title it as a recap, provide a summary, link to the video, and any other resources like the slides. You can then use that same post to drive additional awareness in the community post-event and even prompt for additional questions for the speaker that they can answer in-line.

Thanks @Scott Baldwin  - I used to do a separate post, but it seemed redundant, so I just updated the event. I’ll go back to separate post.