I know this is an older thread, but I want to give some context on captioning:
It's super easy to do yourself now with Youtube's caption editor. I have some personal beef with their choice of hotkeys (anything shift based when you're typing is poorly thought out at best) but it takes maybe three minutes of work per minute of video to open your content up to a very appreciative audience.
And apart from the accessibility benefits of having your content captioned, it plays into your video's SEO ranking as well. Google uses caption content to determine what's actually going on in the video, so they give videos with captions a leg up on ones without because their algorithm can more accurately determine the true nature of the content.