If the closed caption called for applause, as it appears it did...... where do you think the script came from? The WH, that is where.
Uh, you don't seem to understand what closed captioning is. It is a stenographer typing into a computer what is being said or other sounds. So it is the stenographer typing in that applause followed Obama saying the word 'School'. It has nothing to do with a directive from the White House.