diff --git a/youtube_dl/extractor/theplatform.py b/youtube_dl/extractor/theplatform.py
index 7875549b9..7bd530d2d 100644
--- a/youtube_dl/extractor/theplatform.py
+++ b/youtube_dl/extractor/theplatform.py
@@ -144,11 +144,12 @@ class ThePlatformIE(InfoExtractor):
         head = meta.find(_x('smil:head'))
         body = meta.find(_x('smil:body'))
 
+        formats = []
         node = body.find(_x('smil:seq//smil:video'))
         if node is None:
             node = body.find(_x('smil:seq/smil:video'))
         if node is not None and '.m3u8' in node.attrib['src']:
-            formats = self._extract_m3u8_formats(node.attrib['src'], video_id)
+            formats.extend(self._extract_m3u8_formats(node.attrib['src'], video_id))
         if node is not None and '.f4m' in node.attrib['src']:
             f4m_url = node.attrib['src']
             if 'manifest.f4m?' not in f4m_url:
@@ -156,9 +157,8 @@ class ThePlatformIE(InfoExtractor):
             # the parameters are from syfy.com, other sites may use others,
             # they also work for nbc.com
             f4m_url += '&g=UXWGVKRWHFSP&hdcore=3.0.3'
-            formats = self._extract_f4m_formats(f4m_url, video_id)
+            formats.extend(self._extract_f4m_formats(f4m_url, video_id))
         else:
-            formats = []
             switch = body.find(_x('smil:switch'))
             if switch is None:
                 switch = body.find(_x('smil:par//smil:switch'))