[extractor/glomex] Minor fixes
diff --git a/yt_dlp/extractor/generic.py b/yt_dlp/extractor/generic.py
index 529edb59867..7198aa02cc1 100644
--- a/yt_dlp/extractor/generic.py
+++ b/yt_dlp/extractor/generic.py
@@ -1874,6 +1874,7 @@ class GenericIE(InfoExtractor):
             'add_ie': [RutubeIE.ie_key()],
         },
         {
+            # glomex:embed
             'url': 'https://www.skai.gr/news/world/iatrikos-syllogos-tourkias-to-turkovac-aplo-dialyma-erntogan-eiste-apateones-kai-pseytes',
             'info_dict': {
                 'id': 'v-ch2nkhcirwc9-sf',
diff --git a/yt_dlp/extractor/glomex.py b/yt_dlp/extractor/glomex.py
index 247a65a7962..ec3c35c6f5a 100644
--- a/yt_dlp/extractor/glomex.py
+++ b/yt_dlp/extractor/glomex.py
@@ -75,7 +75,7 @@ def _extract_api_data(self, video, video_id):
                     format_url, video_id, 'mp4', m3u8_id=format_id,
                     fatal=False)
                 formats.extend(formats_)
-                subs.update(subs_)
+                self._merge_subtitles(subs_, target=subs)
             else:
                 formats.append({
                     'url': format_url,
@@ -205,8 +205,6 @@ def _extract_urls(cls, webpage, origin_url):
             mdict = mobj.groupdict()
             if mdict.get('url'):
                 url = unescapeHTML(mdict['url'])
-                if url.startswith('//'):
-                    url = f'https:{url}'
                 if not cls.suitable(url):
                     continue
                 yield cls._smuggle_origin_url(url, origin_url)

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### What is the purpose of your *pull request*?
- [ ] Bug fix
- [x] Improvement
- [ ] New extractor
- [ ] New feature

---

### Description of your *pull request* and other information

* Use `_merge_subtitles`
* Do not resolve scheme for embedded URLs
* Add comment to test (in `GenericIE`) for `_extract_urls`