diff --git a/boards/models/attachment/downloaders.py b/boards/models/attachment/downloaders.py
--- a/boards/models/attachment/downloaders.py
+++ b/boards/models/attachment/downloaders.py
@@ -17,7 +17,7 @@ HEADER_CONTENT_TYPE = 'content-type'
 
 FILE_DOWNLOAD_CHUNK_BYTES = 200000
 
-YOUTUBE_URL = re.compile(r'https?://(www\.youtube\.com/watch\?v=|youtu.be/)\w+')
+YOUTUBE_URL = re.compile(r'https?://((www\.)?youtube\.com/watch\?v=|youtu.be/)\w+')
 
 
 class Downloader: