The bedrock of Twitch is its community and a good deal of watching a live broadcast's fun comes from interacting with the regulars who show up in chat. And while you can always check out an archived video if you miss when your favorite streamer goes live, you're missing out on a chunk of the experience because chat wasn't saved along with the clip. Until now. As part of the live-broadcasting service's bigger push toward video-on-demand, Twitch is including the chat log with each previously aired video.
The feature, dubbed "Chat Replay," was actually developed under advisement from the creator of the ReChat browser extension (whom Twitch hired in 2015) so its functionality shouldn't be all that foreign if you had that installed. Twitch says that any unruly users banned or given a time out will have their messages deleted from the chat archive as well, but in a neat twist, anyone with moderator access can delete messages after the initial broadcast too.
So, from the sounds of it, this is much more than Chat Replay simply recording a video of chat and including it in the archive -- chat is almost a kind of living, interactive entity of its own now.
Twitch says that videos made as recently as yesterday will have the chat logs attached, and the feature will begin rolling out over the next few weeks.