[kaltura] Support 'applehttp' containerFormat

This patch adds support for Kaltura video flavors with the
containerFormat 'applehttp'. In this case, the data returned from the url
is an m3u8 file which can subsequently be downloaded normally. This is
what AbcGo uses for its content.

youtube_dl/extractor/kaltura.py

@@ -175,11 +175,18 @@ class KalturaIE(InfoExtractor):
                 unsigned_url += '?referrer=%s' % referrer
             return unsigned_url
 
+        has_native_formats = False
         formats = []
         for f in flavor_assets:
             # Continue if asset is not ready
             if f['status'] != 2:
                 continue
+            if f['containerFormat'] == 'applehttp':
+                m3u8_url = sign_url(info['dataUrl'])
+                formats.extend(self._extract_m3u8_formats(
+                    m3u8_url, entry_id, 'mp4', m3u8_id='hls', fatal=False))
+                continue
+            has_native_formats=True
             video_url = sign_url('%s/flavorId/%s' % (info['dataUrl'], f['id']))
             formats.append({
                 'format_id': '%(fileExt)s-%(bitrate)s' % f,
@@ -193,9 +200,13 @@ class KalturaIE(InfoExtractor):
                 'width': int_or_none(f.get('width')),
                 'url': video_url,
             })
-        m3u8_url = sign_url(info['dataUrl'].replace('format/url', 'format/applehttp'))
-        formats.extend(self._extract_m3u8_formats(
-            m3u8_url, entry_id, 'mp4', 'm3u8_native', m3u8_id='hls', fatal=False))
+
+        if has_native_formats:
+            m3u8_url = sign_url(info['dataUrl'].replace(
+                'format/url', 'format/applehttp'))
+            formats.extend(self._extract_m3u8_formats(
+                m3u8_url, entry_id, 'mp4', 'm3u8_native', m3u8_id='hls',
+                fatal=False))
 
         self._check_formats(formats, entry_id)
         self._sort_formats(formats)