diff --git a/api/api/views/media_views.py b/api/api/views/media_views.py
index 8c33a295b33..906e5974700 100644
--- a/api/api/views/media_views.py
+++ b/api/api/views/media_views.py
@@ -105,6 +105,18 @@ def _get_request_serializer(self, request):
         return req_serializer
 
     def get_db_results(self, results):
+        """
+        Map ES hits to ORM model instances.
+
+        ORM instances have all necessary info needed for serializers whereas ES
+        hits only contain the subset of fields needed for indexing and search.
+        This function issues one query to the DB, using the ``identifier`` field
+        which is both unique and indexed, so it's quite performant.
+
+        :param results: the list of ES hits
+        :return: the corresponding list of ORM model instances
+        """
+
         identifiers = []
         hits = []
         for hit in results: