Some of you may already know that Youtube have just released auto closed captioning in beta version. if you have nitration in your video it will be automatically captioned in English only at present. I have seen a few vidoes with this and it seems to work well. Youtube are going into this big time the idea being to make video more accessible to everyone on the whole planet.
I have manually captioned some of my videos, these can be converted to most languages of the viewers choice. The view count and country of origin rose dramatically after this.
The great thing is Google indexes the contents of the caption .srt file. So if you are thinking of Marketing this is a great SEO tool.
Captioning can be time consuming and fiddly but more than well worth the effort
It would be great to hear your views on this