Members-only live chat

Switch it on from the live chat settings before or during a broadcast. Viewers who are not members carry on watching and can read along, and their participation stops there.

Streams use it for two reasons. Chat moving faster than anyone can read is worthless to everybody in it, and a wave of hostile messages is easier to shut off than to moderate. It also makes membership visibly worth something. The cost is real though: turn it on early in a stream's life and you silence the handful of people about to become regulars.