Blogger enhancement

Hi, I have a blog on [login to view URL] and each post has a player that point to an audio or video file in different formats, formerly mp3, wmv, mkv, avi, mpg. Files are stored in a fileserver that changes its policies constantly. I want to use the Google Appengine blobstore to serve these files, enabling it to play on blogger in a easy way. The users of blog is not very skilled. It is a non profit blog, I think the coder can use the Mediastore as example. The issue is that the blobstore is not recognizing the real file format (mkv e.g).