transmogrifier: When it’s a Video move "url" to "attachment"

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -69,8 +69,8 @@ def contain_origin_from_id(id, %{"id" => other_id} = _params) do
   def fix_object(object) do
     object
     |> fix_actor
-    |> fix_attachments
     |> fix_url
+    |> fix_attachments
     |> fix_context
     |> fix_in_reply_to
     |> fix_emoji
@@ -200,8 +200,14 @@ def fix_url(%{"url" => url} = object) when is_list(url) do
         true -> ""
       end
 
-    object
-    |> Map.put("url", url_string)
+    if Map.get(object, "type") == "Video" do
+      object
+      |> Map.delete("url")
+      |> Map.put("attachment", url_string)
+    else
+      object
+      |> Map.put("url", url_string)
+    end
   end
 
   def fix_url(object), do: object