Before your event
When you create a presentation, you have the choice to upload a Thumbnail and a pre-recorded video to the system that will be visible to a guest to watch your content before your live event.
After a live stream
When you complete your live event, you can go to the stream admin area and then edit your clip, upload a thumbnail and save the clip.
The category of your presentation is what will be used as the catch-up category.
Categories show only in alphabetical order, and if there are no assets associated with a category, the category will not be visible.