Added two hooks that are provided via info_dict from extractor under keys '_fragment_hook_before_dl' and '_fragment_hook_after_dl' that run before and after fragment is downloaded.

yt_dlp/downloader/fragment.py

@@ -121,12 +121,21 @@ class FragmentFD(FileDownloader):
             frag_resume_len = self.filesize_or_none(self.temp_name(fragment_filename))
         fragment_info_dict['frag_resume_len'] = ctx['frag_resume_len'] = frag_resume_len
 
+        execute_before_frag_dl = info_dict.get('_fragment_hook_before_dl')
+        if execute_before_frag_dl is not None and callable(execute_before_frag_dl):
+            execute_before_frag_dl(fragment_filename, fragment_info_dict, ctx)
+
         success, _ = ctx['dl'].download(fragment_filename, fragment_info_dict)
         if not success:
             return False
         if fragment_info_dict.get('filetime'):
             ctx['fragment_filetime'] = fragment_info_dict.get('filetime')
         ctx['fragment_filename_sanitized'] = fragment_filename
+
+        execute_after_frag_dl = info_dict.get('_fragment_hook_after_dl')
+        if execute_after_frag_dl is not None and callable(execute_after_frag_dl):
+            execute_after_frag_dl(fragment_filename, fragment_info_dict, ctx)
+
         return True
 
     def _read_fragment(self, ctx):

yt_dlp/extractor/common.py

@@ -389,6 +389,16 @@ class InfoExtractor:
                     extracted will not be available to output template and
                     match_filter. So, only "comments" and "comment_count" are
                     currently allowed to be extracted via this method.
+    _fragment_hook_before_dl: A function to be called just before fragment is
+                    downloaded. It should take three positional arguments:
+                    'fragment_filename', 'fragment_info_dict' and 'ctx'.
+                    This is useful for special sites that need to change
+                    access cookies on every fragment/every few seconds.
+    _fragment_hook_after_dl: A function to be called right after fragment is
+                    downloaded. It should take three positional arguments:
+                    'fragment_filename', 'fragment_info_dict' and 'ctx'.
+                    This is useful for special sites that need to change
+                    access cookies on every fragment/every few seconds.
 
     The following fields should only be used when the video belongs to some logical
     chapter or section: