Captions can greatly enhance the experience of viewing a YouTube video, and the YouTube API has offered developers ways to upload and retrieve caption data in authorized requests for a while now. Google today, launched the "YouTube Captions Uploader,' an open source project on Google Code, which provides real-world code for uploading captions to YouTube.
The code is written for the Java App Engine environment, and it uses some nifty new App Engine features like the Channel API, the Blobstore Service, and Task Queues. And even if you're not an App Engine developer, we hope that the code that interacts with the YouTube API's captions service will provide a good starting point for writing your own code.
If you'd like to use the YouTube Captions Uploader without having to deploy your own App Engine instance, a public example is running at http://yt-captions-uploader.appspot.com/. If you're a developer who wants to run your own instance, perhaps with code modifications, then continue reading!
More Info: YouTube Captions Uploader