There are a lot of videos on YouTube in which people answer questions about themselves. Usually, at least ostensibly, the questions are posed by viewers. This provides an excuse for the person posting the video to talk about something they know about, namely, themselves. Basically, it's an easy way to come up with material to use in a video. Also it's something that many big YouTubers do and so it seems like a perfectly reasonable and respectable kind of video to make and post. Of course, the vast majority of these videos never receive many views, but sometimes revealing information about oneself is a way to draw viewers into what is sometimes called a virtual relationship. Obviously, the risk of over-sharing is always something to consider, but answering harmless questions seems like a reasonable and fun thing to do for the most part.