I'm curious how that works. It decodes the FLAC in JavaScript, but it still has to expose it in some format understood by the browser. To my limited knowledge there's no lossless encoding scheme supported by browsers, not even WAV PCM.

/edit: spoken too soon WAV PCM is supported by WebKit, Gecko and Presto: http://en.wikipedia.org/wiki/HTML5_Audio#.3CAudio.3E_element