In this chapter, analysis focuses principally on asynchronous substrand comments on an Ethan Gamer YouTube video, which are elicited by single main strand comments. Analysis reveals that in most instances, YouTube main and substrand comments interaction has a unique one-way structure, where comments by individual users are addressed mainly to the producer and participant of the video, in this case Ethan Gamer, or to the commenter who posts the main strand comment which elicits the substrand. While adjacency and sequence are disrupted by various software features in the main strand comments, sequentiality is adhered to in the substrand comments where users have access to meaningful written interaction and conversational sequences. However, Ethan Gamer’s replies to commenters’ posts are infrequent. Nonetheless, Ethan Gamer YouTube commenters use the substrand comments tool to connect with both unknown and familiar other users, engaging mainly in talk about gaming hardware, Ethan Gamer’s gameplay, and sometimes to clarify their actual age where adults’ accounts are being used to access YouTube. Nostalgic YouTube substrand posts may also comprise tellings, which suggest commenters’ social orientation through a search for commonality with other users.

The chapter discusses how interlocutors jointly optimize the timing of their contributions. It considers how they interleave their dialogue plans so that the steps are properly sequenced (e.g., an answer follows a question). It then considers how their contributions are interleaved so as to avoid overlap but with minimal gaps. Finally we consider how interlocutors entrain their speech rates to support coordinated speech planning and production.