Fixed typo

youtube_dl/YoutubeDL.py

@@ -232,7 +232,7 @@ class YoutubeDL(object):
             # On Python 3, the Unicode filesystem API will throw errors (#1474)
             self.report_warning(
                 'Assuming --restrict-filenames since file system encoding '
-                'cannot encode all charactes. '
+                'cannot encode all characters. '
                 'Set the LC_ALL environment variable to fix this.')
             self.params['restrictfilenames'] = True