[downloader/external] Recommend --hls-prefer-native for SOCKS users

Related: #10490

youtube_dl/downloader/external.py

@@ -223,7 +223,8 @@ class FFmpegFD(ExternalFD):
 
             if proxy.startswith('socks'):
                 self.report_warning(
-                    '%s does not support SOCKS proxies. Downloading may fail.' % self.get_basename())
+                    '%s does not support SOCKS proxies. Downloading is likely to fail. '
+                    'Consider adding --hls-prefer-native to your command.' % self.get_basename())
 
             # Since December 2015 ffmpeg supports -http_proxy option (see
             # http://git.videolan.org/?p=ffmpeg.git;a=commit;h=b4eb1f29ebddd60c41a2eb39f5af701e38e0d3fd)