Translating the Audio player interface in WP Core

I’ve been trying to find where I can get access to translate the overlay text for the Audio Player in WordPress 4.1.1.

I you have an audio element hosted locally and load it using the [audio] shortcode, it puts an audio player in the browser. If you click on and drag the time bar, an overlay pops up with the following text:

“Use Left/Right Arrow keys to advance one second, Up/Down arrows to advance ten seconds”

I want to translate this text into another language for my site usage. However, the phrase does not appear when I generate a .PO file using Poedit on the site. It looks like this text might be housed inside of the .js file that runs the audio player.

Where can I go about finding this, and changing it manually? Or is there a way to generate a translation using the normal workflow of a .PO to .MO file?