(This is an addon that just works. Don't expect fancy UI) Features

🎞️ Display as many subtitles as you like (multiple subtitles Youtube)
🎞️ Support auto-generated subtitle also
🎞️ Support machine-translated subtitle also (including translating from auto-generated)
You should know machine-translate is not 100% correct. It could contain lots of mistakes
🛡️ No third-party server needed
🛡️ No confliction with Youtube web player's CC
🛡️ Maximum safety. No injection if you don't click the toolbar button. Minimum permission required.

More of my addons Youtube has videos that provide subtitles (CC, closed captions) in different languages, but will not display more than one simultaneously on itself's web player. Why not display several at the same time? Why not? Nothing fancy, this is a browser addon that works! Watch with two subtitles on. Even more, three, four, five ... Simultaneously. Display as many as you like! Different languages, translated, auto-generated ... Useful for learning foreign languages. Testing videos

Give it a star on Github !