1) Offline auto-captioning in languages other than English

Automatic captioning (generated by machine using speech recognition software) is available currently in 10 languages

However, you can upload human-created captions in any language, and even with automatic captions you should still do this as they tend to have a lot of errors. What many people do is to start with the "automatic caption" track by downloading it, editing it, and uploading it back as a clean, accurate track.  This help center article is a good place to start.

2) Offline caption auto-translation into English

Any viewer can, during playback, ask for the captions to be auto-translated into any of the 50-plus other languages we support.  The accuracy varies depending on the language pairs -- usually English->X is the most accurate for most values of X.

There is a new feature described in this blog post and this help center page, that allows you to get captions professionally translated, (hopefully for modest prices).

 http://www.amara.org/en/ is another option that can be used to create/translate captions -- they use a special API to interact with YouTube.

* I refer to offline above meaning this works any video held on YouTube but not for live Hangouts on Air currently (although once they are on YouTube you can do it).