Here is a site that allows you to subtitle youtube videos. It works by attaching a wiki subtitle line, so that you (or anyone else) can subtitle a video in any language you know. There is a fun little demo that you can play with, without registering, that shows off its capabilities. Using dotsub.com is free – and allows a video to be translated into any language and to be assessible to the hearing-impaired! It does not look like it currently does automatic translation like the Universal Translator in Star Trek.