[limelight] Improve and make more robust (closes #11737)

+ Add support for direct http for videos hosted on video.llnw.net
* Check handmade http URLs

youtube_dl/extractor/limelight.py

@@ -59,14 +59,26 @@ class LimelightBaseIE(InfoExtractor):
                     format_id = 'rtmp'
                     if stream.get('videoBitRate'):
                         format_id += '-%d' % int_or_none(stream['videoBitRate'])
-                    http_url = 'http://cpl.delvenetworks.com/' + rtmp.group('playpath')[4:]
+                    http_format_id = format_id.replace('rtmp', 'http')
+
+                    CDN_HOSTS = (
+                        ('delvenetworks.com', 'cpl.delvenetworks.com'),
+                        ('video.llnw.net', 's2.content.video.llnw.net'),
+                    )
+                    for cdn_host, http_host in CDN_HOSTS:
+                        if cdn_host not in rtmp.group('host').lower():
+                            continue
+                        http_url = 'http://%s/%s' % (http_host, rtmp.group('playpath')[4:])
                         urls.append(http_url)
+                        if self._is_valid_url(http_url, video_id, http_format_id):
                             http_fmt = fmt.copy()
                             http_fmt.update({
                                 'url': http_url,
-                        'format_id': format_id.replace('rtmp', 'http'),
+                                'format_id': http_format_id,
                             })
                             formats.append(http_fmt)
+                            break
+
                     fmt.update({
                         'url': rtmp.group('url'),
                         'play_path': rtmp.group('playpath'),