+        def fail(message):
+            raise ExtractorError(
+                'Unable to login. Twitch said: %s' % message, expected=True)
+
+        def login_step(page, urlh, note, data):
+            form = self._hidden_inputs(page)
+            form.update(data)
+
+            page_url = urlh.geturl()
+            post_url = self._search_regex(
+                r'<form[^>]+action=(["\'])(?P<url>.+?)\1', page,
+                'post url', default=page_url, group='url')
+            post_url = urljoin(page_url, post_url)
+
+            headers = {'Referer': page_url}
+
+            try:
+                response = self._download_json(
+                    post_url, None, note,
+                    data=urlencode_postdata(form),
+                    headers=headers)
+            except ExtractorError as e:
+                if isinstance(e.cause, compat_HTTPError) and e.cause.code == 400:
+                    response = self._parse_json(
+                        e.cause.read().decode('utf-8'), None)
+                    fail(response.get('message') or response['errors'][0])
+                raise
+
+            if 'Authenticated successfully' in response.get('message', ''):
+                return None, None
+
+            redirect_url = urljoin(
+                post_url,
+                response.get('redirect') or response['redirect_path'])
+            return self._download_webpage_handle(
+                redirect_url, None, 'Downloading login redirect page',
+                headers=headers)
+