Where are these files stored? Internal static APEX files under Shared Components? Your own table with a blob?
When stored in my own tables, I often had to manually (with my own code after upload) set my MIME_TYPE when I upload files because the mime type file in the webserver is not correctly configured.
MIME_TYPE,DATE,CHAR_SET,FILE_NAME these column available in your table? it could be play abort from the apex application.you can download and play! if you want play within apex page,you have to add plug-in.