First person: Talking about oneself. I, me.
Second person: talking about the listener. you, your.
Third person: talking about someone who is not the speaker or listener. He/she/it/they
Fourth person: Talking about total bullshit.
In this context, "Chat" is second-person plural, used by streamers to address the portion of their audience able to respond in the text chat that always accompanies these things. It does contrast with how a radio personality might address "listeners" because radio listeners don't usually have a method to respond in real time, so it's usually a rhetorical question; a streamer addressing the chat is asking for a response.
There are languages with a 4th person pronoun. The 3rd person is kind of the main character and the 4th someone else. That helps to disambiguate sentences like "The criminal shot the cop and drove away on his (own or the cop's) bike".
Or the "gay fanfiction problem": "He looked at him and lay his hands on his lap". Is it a happy ending or a sad one? That's one theory why gender in pronouns is so resilient: more often than not, the gendered pronoun can disambiguate which person is talked about. It doesn't always work, a 3rd/4rd person distinction is superior.
My rl name starts with Chat and I introduce myself as such most places. It's pronounced differently though, since it's based on a French word. The Ch has an Sh sound. And yes, I know what that sounds like...
Probably has something to do with meat crayons video, I've been hanging out with some 20 year olds in discord and theh routinely make jokes based off this video.
But have they begun unwittingly emulating the ancient Greek chorus yet, or is this that? In either event, I'm amused, but slightly moreso with the former of entire groups addressing their situation