[twitcasting] Don't return multi_video for archive with single hls manifest (#3319)

Authored by: Lesmiscore

yt_dlp/extractor/twitcasting.py

@@ -183,6 +183,14 @@ def find_dmu(x):
             infodict = {
                 'formats': formats
             }
+        elif len(m3u8_urls) == 1:
+            formats = self._extract_m3u8_formats(
+                m3u8_urls[0], video_id, 'mp4', headers=self._M3U8_HEADERS)
+            self._sort_formats(formats)
+            infodict = {
+                # No problem here since there's only one manifest
+                'formats': formats,
+            }
         else:
             infodict = {
                 '_type': 'multi_video',