In a rather long winded way she explains to her potential viewers the reason she is starting a youtube channel, that explanation is literally "Why not?"
1st Video: Hi I am Nicola, aka Youtuber, aka Worlds Best Youtuber, many might think "oh no, not another one" , I thought: Why not?
2nd Video: Since nobody can go to the gym right now anyway, some of you might want some tips, some don't, watch if you want, otherwise don't.
3rd Video: I don't want every crap myself either.
Sort of a shortened version of what she said. Boils down to her being bored I think. (And potentially IG cracking down on certain posts, probably not hers though, but it's smart to diversify your social media presence, and on Twitch you have to deal with livestreaming and idiots in chat, on YT you can just do videos and upload them and ignore comments.)