YouTube is opening up its auto-caption feature to everybody, a move that benefits not only deaf users, but also people who watch videos in really noisy places, like airport terminals. And since the tool will be able to translate captions into your choice of 50 languages, it should be handy for viewing YouTube clips from around the world. (For now, however, auto-captioning works only with videos in English.)

Auto-captioning borrows some text-to-speech algorithms from Google Voice Search to automatically create captions upon viewer request. As you'd expect from machine-generated captioning, the results aren't perfect, but they're fairly accurate for formal presentations and keynote-type speeches with minimal background noise. In other words, auto-captioning gives you a pretty good idea of what's being said, although some of the finer points may be misleading or just plain wrong. On the plus side, a video owner can download the auto-captions, clean them up, and upload a corrected transcript.

The iPad Keynote Test

To test auto-captioning, I went to YouTube to watch Steve Jobs' iPad presentation from January 2010. The feature is a cinch to activate via the "up arrow" button on the bottom right of the video window:

Within seconds, YouTube begins generating captions, which it displays in real-time:

Auto-captioning was reasonably accurate, albeit with a few glitches, such as:

· Steve: And you can change the background screen, the home screen, to personalize it any way you want.

· YouTube: and you cannot change the background screen the whole screen that personalize it anyway you want

· Steve: You can browse the Web with it

· YouTube: you can browse the went with it

· Steve: A keyboard pops up. It's almost life-size.

· YouTube: a keyboard pops up it's almost like flies

YouTube first released auto-captioning to a small group of beta testers in November. The wide availability of this tool will certainly benefit content owners, who can easily and quickly make their videos accessible to a worldwide audience.

Then again, a poorly translated video could lead to some troubling international incidents. What do you think?