Start off with landing.php. There are so many bogus files including index.php.
Updating the records, if no value is selected for actor and genre it would update null and displays blank. Updating an actor or genre should be followed or be done after any change in other columns, as updating actor/genre column alone has been set not to act. It's the expected behaviour.
Click anywhere outside the table after edit to get it done as you wont see no submit button.