review: expand on why returning no flow segment get_urls could be useful

Co-authored-by: Andrew Gibb <[email protected]>

api/TimeAddressableMediaStore.yaml

@@ -1296,6 +1296,8 @@ paths:
             A comma separated list of labels of flow segment `get_urls` to include in the response.
             A 'default' label selects URLs with a 'default' or no label.
             An empty `accept_get_urls` results in an empty or no `get_urls` flow segment property in the response.
+            Without `get_urls`, the response from the service could be substantially faster if it is not required to
+            generate a large number of pre-signed URLs for example.
           schema:
             type: string
             pattern: ^[^,]*(,[^,]*)*$
@@ -1395,6 +1397,8 @@ paths:
             A comma separated list of labels of flow segment `get_urls` to include in the response.
             A 'default' label selects URLs with a 'default' or no label.
             An empty `accept_get_urls` results in an empty or no `get_urls` flow segment property in the response.
+            Without `get_urls`, the response from the service could be substantially faster if it is not required to
+            generate a large number of pre-signed URLs for example.
           schema:
             type: string
             pattern: ^[^,]*(,[^,]*)*$