Replace YouTube captions from Emacs Lisp

I want to be able to easily update YouTube captions from my VTT files. Adding a comment like this: NOTE #+YOUTUBE_URL: https://youtu.be/sxqsIgXYkVw #+LANGUAGE: en to the first subtitle in my VTT file lets me programmatically replace the captions for the specified language without needing to click through the YouTube interface, saving me at least 9 clicks, a slight delay, and the selection of the…