Fixed filepath bug when embedding thumbnails

yt_dlp/postprocessor/embedthumbnail.py

@@ -224,4 +224,8 @@ class EmbedThumbnailPP(FFmpegPostProcessor):
             thumbnail_filename if converted or not self._already_have_thumbnail else None,
             original_thumbnail if converted and not self._already_have_thumbnail else None,
             info=info)
+
+        if not self._already_have_thumbnail:
+            del info['thumbnails'][idx]['filepath']
+
         return [], info