That is a lovely thought, Steven, but it unfortunately has a downside. Unless the video poster has manually reviewed and corrected the close captioning, that function within YouTube is entirely automated and produces some highly questionable output. Sometimes this is OK - other times, it is not. You can see an example of this in the first 30 seconds of the ten minute 'Suggestions Report' video, which has automatically generated closed captioning.
In addition, YouTube CC is not particularly accessible to screen readers or translation software, as again, unless it has been edited, it typically lacks any form of coherency in regards to use of punctuation. This is why a text transcription posted to the comments was requested. That is typically less work for a video poster than editing the closed captioning, as it does not have to be synchronized to the video feed. It can also be more screen-reader friendly, as scrolling text can play poorly with screen readers (especially braille readers).
This subject is of a special interest to me, as I have family, friends, and coworkers with varying degrees of visual and hearing impairments, so I prefer to raise the question on their behalf since so few people inherently think of this population when designing a new item - but they are just as interested (often more so!) in genealogical research as someone who has typical visual/auditory function.