The split necklace puzzle (with a surprise topological solution)

A link to the full video is at the bottom of the screen.
Or, for reference: https://youtu.be/yuVqxCSsE7c
A puzzle about stolen necklaces, from a video about the Borsuk Ulam theorem in topology

Editing from long-form to short by Dawid Kołodziej

Видео The split necklace puzzle (with a surprise topological solution) канала 3Blue1Brown