For the White House, the most devastating segment of "Fahrenheit 9/11" may be the video of a befuddled-looking President Bush staying put for nearly seven minutes at a Florida elementary school on the morning of Sept. 11, continuing to read a copy of "My Pet Goat" to schoolchildren even after an aide has told him that a second plane has struck the twin towers. Mr. Bush's slow, hesitant reaction to the disastrous news has never been a secret. But seeing the actual footage, with the minutes ticking by, may prove more damaging to the White House than all the statistics in the world.