I noticed she had replied to almost every question on her video, and she was kind enough to answer ours, just for the record:
Emma, I was curious, do the paid sponsorships come directly from the publishers? Or are they coming from author-hired publicists / 3rd party marketers working on behalf of the publishers? When someone says 'sponsored by HarperCollins', is there another entity involved between them and the Booktuber?
Justin sometimes!!! It depends but even if you are being contacted by a company that's hired by the publisher, the sponsorship (books, materials, the actual payment) is still from the publishers, so the sponsor is the publisher. It can really be either!
For anyone not familiar with the booktube community, it's really a small group of around 10 to 20 book vloggers who have sponsored content (their followers ranging in amounts from about 10k to 300k), and probably a few hundred more without as much influence. It's a different realm than written blog reviews, but there is overlap on social media, and their opinions on books are consistent across the board.