I think he was sincere in the video and he is indecisive but at the same time , immediately after he makes a video saying he isn't retiring. He is a youtuber, no video on youtube is really sincere, its planned, calculated, for an intended effect. I am not saying that in a negative way. Maybe both things were present at once, he became emotional over the 10 million milestone and started to reconsider his career/future and also saw a good opportunity to make a video about it.