Google recently added subtitles & captions feature to its YouTube video service. However, if you want to auto-translate subtitles on videos in your natvie language. The video must have captions enabled, if it doesn’t – just add this &cc_load_policy=1 into the embed code. Once activated, click the bottom right, then click the arrow by the “CC”. Choose “Translate” from the pop-up menus, and then select your language to translate the captions into, and in a few seconds, you can watch video and read the subtitles in your desired language. The Google Translate recently added seven new languages.
Source:→ Matt Cutts