[viewster] use head request to extract api token

Closes #6419.

youtube_dl/extractor/viewster.py

@@ -11,6 +11,7 @@ from ..utils import (
     determine_ext,
     int_or_none,
     parse_iso8601,
+    HEADRequest,
 )
 
 
@@ -73,7 +74,7 @@ class ViewsterIE(InfoExtractor):
     def _real_extract(self, url):
         video_id = self._match_id(url)
         # Get 'api_token' cookie
-        self._request_webpage(url, video_id)
+        self._request_webpage(HEADRequest(url), video_id)
         cookies = self._get_cookies(url)
         self._AUTH_TOKEN = compat_urllib_parse_unquote(cookies['api_token'].value)