Using it for better subtitle support on english dubs. In other words, this enables me to select the English subtitles that are used when watching something with Japanese audio versus the default English CC subtitles that are available when watching English dubs. English CC subtitles are usually pretty poorly done, as it is a simple automatic speech-to-text tool and very often interprets what words are being spoken incorrectly. As such, the English subtitles available when watching with Japanese audio are far more accurate/better and this extension lets me select those on the videos I've watched, so this gets a 5 out of 5 stars for my needs.