Add .to_stderr() to downloaders

youtube-dl

@@ -149,6 +149,10 @@ class FileDownloader(object):
 			sys.stdout.write('%s%s' % (message, ['\n', ''][skip_eol]))
 			sys.stdout.flush()
 	
+	def to_stderr(self, message):
+		"""Print message to stderr."""
+		sys.stderr.write('%s\n' % message)
+
 	def download(self, url_list):
 		"""Download a given list of URLs."""
 		for url in url_list:
@@ -170,30 +174,30 @@ class FileDownloader(object):
 					try:
 						filename = self._params['outtmpl'] % result
 					except (KeyError), err:
-						sys.stderr.write('ERROR: invalid output template: %s\n' % str(err))
+						self.to_stderr('ERROR: invalid output template: %s' % str(err))
 						continue
 					try:
 						self.pmkdir(filename)
 					except (OSError, IOError), err:
-						sys.stderr.write('ERROR: unable to create directories: %s\n' % str(err))
+						self.to_stderr('ERROR: unable to create directories: %s' % str(err))
 						continue
 					try:
 						outstream = open(filename, 'wb')
 					except (OSError, IOError), err:
-						sys.stderr.write('ERROR: unable to open for writing: %s\n' % str(err))
+						self.to_stderr('ERROR: unable to open for writing: %s' % str(err))
 						continue
 					try:
 						self._do_download(outstream, result['url'])
 						outstream.close()
 					except (OSError, IOError), err:
-						sys.stderr.write('ERROR: unable to write video data: %s\n' % str(err))
+						self.to_stderr('ERROR: unable to write video data: %s' % str(err))
 						continue
 					except (urllib2.URLError, httplib.HTTPException, socket.error), err:
-						sys.stderr.write('ERROR: unable to download video data: %s\n' % str(err))
+						self.to_stderr('ERROR: unable to download video data: %s' % str(err))
 						continue
 				break
 			if not suitable_found:
-				sys.stderr.write('ERROR: no suitable InfoExtractor: %s\n' % url)
+				self.to_stderr('ERROR: no suitable InfoExtractor: %s' % url)
 	
 	def _do_download(self, stream, url):
 		request = urllib2.Request(url, None, std_headers)