November 4th, 2009 | Published in Youtube API
It's been several years since we've released the Google Data-based YouTube API, and in that time we've been encouraging developers who used the legacy YouTube API to upgrade before we pull the metaphoric plug on that older version. At this point, all but a handful of holdouts have upgraded, and as of November 11, 2009, the legacy YouTube API will cease operation.
If you're using one of our YouTube API client libraries, then you're definitely making use of the modern Google Data YouTube API. If you're manually making HTTP requests to a URL whose hostname contains gdata.youtube.com, then you're also good to go. If you think you might still be using the legacy YouTube API but aren't sure, take a look at some of the example legacy API calls in this migration guide. If it turns out that you are still using the older API, then the migration guide will give you the information you need to upgrade – and be sure to do so before November 11!