I create language learning videos and having captions both in Spanish or in English is one of the most useful features for students, they can decide if they watch the content with or without them. Also, it allows users in general to enjoy any content and watch videos without using earphones, or in any place where turning on the speakers is inconvenient. This is one of the most successful strategies for video creators on instagram, for example. Ofc, we could insert the captions in the edition process, but I think being able to choose the language, and turning on and off is important.