Working demo: http://davidmz.github.com/apng-canvas/ (around 3 Mb of apng files)
Another Demo: http://clientes.netvisao.pt/ijosemar/white-spinner-test/test.html
Discussion in LJ: http://david-m.livejournal.com/tag/apng-canvas (in russain) -> Link translated to English
The library creates a global object APNG, which has several methods. All methods are asynchronous and most of them receive an optional callback-argument. Methods must be called after DOM tree is loaded.
For deferred calls, these methods return promise objects. If jQuery is available, then its promises are used, in other case a compatible interface which supports methods done, fail, then and always is used.
If the method is finished successfully, callback and done handlers are called (with the same parameters), in case of error fail hendlers are called with the error message.
APNG Samples: http://www.darrenburnhill.com/graphics/apng_samples.php