A List Apart: Articles: This is How the Web Gets Regulated
http://www.alistapart.com/articles/thisishowthewebgetsregulated

about captioning

This blog entry shows you how to create automatic captions for you YouTube videos.

"In addition to automatic captions, we’re also launching automatic caption timing, or auto-timing, to make it significantly easier to create captions manually. With auto-timing, you no longer need to have special expertise to create your own captions in YouTube. [...]"

"To help address this challenge, we've combined Google's automatic speech recognition (ASR) technology with the YouTube caption system to offer automatic captions, or auto-caps for short. Auto-caps use the same voice recognition algorithms in Google Voice to automatically generate captions for video. The captions will not always be perfect (check out the video below for an amusing example), but even when they're off, they can still be helpful—and the technology will continue to improve with time."

YouTube now does automatic captioning in some cases and automatic timing in all cases. Automatic timing lets you upload a transcript with a video and YouTube will do speech to text and figure out when the various parts of the transcript need to be displayed.