What Did Card Really Whisper to Bush on 9/11?

Chief of Staff Andrew Card states in this recollection of 9/11 that he whispered to President Bush "A second plane hit the second tower. America is under attack".

This wmv video shows Card delivering his message to Bush, and it demonstrates the speed at which he would have had to have to spoken the above words.

It is impossible to whisper at this speed, so why have both he and Bush lied about the content of the message?

Why did the 9/11 Commission ignore this lie?

The President was seated in a classroom when, at 9:05, Andrew Card whispered to him: "A second plane hit the second tower. America is under attack." [9/11 Commission Report]