coursera 视频双字幕显示

https://greasyfork.org/fi/scripts/382357-coursera%E5%BC%80%E5%90%AF%E4%B8%AD%E8%8B%B1%E5%8F%8C%E5%AD%97%E5%B9%95-coursera-subtitle-cn-en?locale_override=9%27A%3D0+HACK+AGARIO+COINS