The Tor Browser / file revision

 // Serve a media file without using content-range header

 function handleRequest(request, response)

 {

   var file = Components.classes["@mozilla.org/file/directory_service;1"].

                         getService(Components.interfaces.nsIProperties).

                         get("CurWorkD", Components.interfaces.nsILocalFile);

   var fis  = Components.classes['@mozilla.org/network/file-input-stream;1'].

                         createInstance(Components.interfaces.nsIFileInputStream);

   var bis  = Components.classes["@mozilla.org/binaryinputstream;1"].

                         createInstance(Components.interfaces.nsIBinaryInputStream);

   var paths = "tests/content/media/test/320x240.ogv";

   var split = paths.split("/");

   for(var i = 0; i < split.length; ++i) {

     file.append(split[i]);

   }

   fis.init(file, -1, -1, false);

   bis.setInputStream(fis);

   var bytes = bis.readBytes(bis.available());

   response.setStatusLine(request.httpVersion, 200, "Content Follows");

   response.setHeader("Content-Type", "video/ogg", false);

   response.write(bytes, bytes.length);

   // Make this request async to prevent a default Content-Length from being provided.

   response.processAsync();

   response.finish();

   bis.close();

 }