A New Format for JSON Results
It's been two and a half years since we announced JSON as an alternative output format to Atom XML for YouTube API responses. As illustrated in the developer's guide and codelab, JSON-formatted data is a natural choice when writing web applications – after all, who wants to parse XML from JavaScript?
We've rethought out current JSON implementation, and moved away from a literal representation of the Atom data to a format that we hope will be more pleasing to those who are fluent in JSON. The vestigial XML namespace prefixes are no more, and we've removed many pieces of metadata specific to Atom documents that come across as noise in JSON. Repeating data elements are always structured as true JSON lists, and useful video metadata that exist as XML attributes in Atom have been rearranged to make more sense in the JSON document. You'll also find that the new JSON results are more compact than Atom XML, which is of special importance to code running from limited-bandwith mobile applications.

