Oh wow, this works better than I expected. No issues whatsoever so far, it's plug and play. It even plays nice with my other addons that alter the netflix UI.
I may have a suggestion: would it be possible to include an option to add furigana? Maybe even make them easily toggleable by keyboard shortcut? Right now I'm using 10ten Reader on top of this addon to get readings where the audio isn't clear enough, which does work but it's a bit clunky. I do realise that the add-on would have to pull the readings from somewhere which probably wouldn't always work perfectly (and might be too resource-heavy?) but I think this could help even more with listening comprehension.