[Solved].
I messed up the Messaging Syntax.
s.send(messageTemp + "\r\n")
I forgot to append the end characters to my messages. I imagine they were sent, but the server never posted them into chat because it was never told that was the end of my message. How embarrassing; just one thing I missed while trying to keep up with the video. (Source code was linked to in description, which is how I noticed this error.)