diff --git a/yt_dlp/extractor/common.py b/yt_dlp/extractor/common.py
index d5607296d..6dcb26830 100644
--- a/yt_dlp/extractor/common.py
+++ b/yt_dlp/extractor/common.py
@@ -1675,8 +1675,8 @@ def extract_video_object(e):
                 'ext': mimetype2ext(e.get('encodingFormat')),
                 'title': unescapeHTML(e.get('name')),
                 'description': unescapeHTML(e.get('description')),
-                'thumbnails': [{'url': unescapeHTML(url)}
-                               for url in variadic(traverse_obj(e, 'thumbnailUrl', 'thumbnailURL'))
+                'thumbnails': [{'url': unescapeHTML(url if not url.startswith('//') else 'https:' + url)}
+                               for url in variadic(traverse_obj(e, 'thumbnailUrl', 'thumbnailURL', 'thumbnail_url'))
                                if url_or_none(url)],
                 'duration': parse_duration(e.get('duration')),
                 'timestamp': unified_timestamp(e.get('uploadDate')),