The sentence stops right before the verdict, and his sideways glance says the answer is not simple. The sheer size of the book makes the effort plain to see. So the question becomes whether the climb was worth it.
How the packaging works
Title
It sets up a huge reading effort and cuts off before the verdict.
Thumbnail
It shows the massive book and a doubtful sideways glance at it.
Remix this
Use an unfinished title only when the image shows the thing being judged and your face shows a clear reaction. Without that tension the trailing dots just look like a mistake.
The transferable lesson
An unfinished sentence needs a readable face
NicheBooks
Click driverCuriosity Gap
Turn the lesson into a decision
Apply this pattern to your next video.
Bring the reference into a packaging brief, then decide what your title and thumbnail should each communicate.