I know it is possible to play video and audio, but I think it would be an error to mistake the image gallery software for audio or video software, because the images have been replaced by video or audio. That doesnt make it a handy music player or video directory.
Its probably a small leap from current photopost layout & functionality to a youtube like setup. If users can do anything they can do on youtube and if admins can replicate the design, then I think you are there.
From the current image gallery setup to a music system (
SoundCloud - Your Sound, At The Heart ,
Last.fm - Listen to free music with internet radio and the largest music catalogue online , etc) it is a bigger leap in terms of layout and functionality.