Feature: Enable a mechanism to show/hide captions on-demand

[JavierMartinz]

Currently, there is a possibility to autoplay a muted video with a captions track shown. However, there is no way to, for instance, hide those captions if user disables muted.

Since the video is behind and iframe, there is no way to access to the tracks and hide them using something like

videoRef.textTracks[0].mode = 'hidden'

[kensnyder]

I too need this feature because I am implementing my own controls.