To enable the chat for a live event, toggle the "Chat" button on the media page of the live event.
Clicking the "Administer" button takes you to the admin interface of the chat. From the admin interface, you can remove posted messages and send messages as "Admin".
Once enabled, the chat will appear below the video in any preview links and if the video is published on a videosite the chat will also appear below the video there.
Before posting a message, the viewer will be prompted to enter their name and verify that they are human.