The feature is called <a href="https://docs.joinpeertube.org/admin/following-instances#instances-redundancy" target="_blank">"server redundancy"</a> and caches your most popular videos to help serve additional viewers.
Communicate with the streamer and other viewers using the <a target="_blank" rel="noopener noreferrer" href="https://livingston.frama.io/peertube-plugin-livechat/">livechat PeerTube plugin</a>
Communicate with your viewers using the <a target="_blank" rel="noopener noreferrer" href="https://livingston.frama.io/peertube-plugin-livechat/">livechat PeerTube plugin</a>