Adding captions and subtitles to HTML5 video

Hello again @chrisdavidmills. I did the “Captioned video example”. I encountered some difficulty with the subtitles, I don’t understand why they don’t work.
I don’t know if you can mark it as there is a video inside and on CodePen it can’t be reproduced. Anyway, if you want to take a look this is the URL : https://codepen.io/Andreea96/pen/BaymoKL .