As a Speaker
From your, Speaker Dashboard you can see all the talks you'll be hosting under My Talks. You can see your pre-recorded or replay talks under the Manage drop-down and click 'View Recording.'
If you have an upcoming talk, the dropdown should have the Preview Talk Page option. If you click on Preview Talk Page, you'll see a screen like the one below. This is a preview of the public
talk page and what attendees see before a session starts.
To view the session while it's live, click Broadcast view. To view it after it was live, click on Replay View.
Note that there isn't a way to test the video settings when hosting live sessions as they haven't started yet. You can only test or preview pre-recorded sessions.
This is the screen your attendees will see if your replays haven't been uploaded yet or you haven't disabled replays (if you're not planning to show the videos on-demand)
Event Organizers can also preview talk pages from their Dashboard.