I think I overestimated this thread's familiarity with YouTube subtitles. I only took an interest in them when I found out you can mess around with fonts, colors, etc.
YouTube auto-generates subtitles for videos using speech-to-text, but they can be edited/replaced with something else.
Some people like to fuck around with default subtitles. Someone replaced the auto-generated subs in JayExci's Doctor Who video, which is 5 hours long, with a Korean translation. In order to get English subtitles, you need to have YouTube auto-translate the Korean subs to English.