Tasteless and disgusting. Horrifyingly disrespectful. Have some respect for the lives that were lost and the horror of the events of 9/11. The disregard for human life is disgusting, particularly the selection of the man jumping out of the building. Liberace would be aghast, I imagine, if he knew that his performance of an uplifting song was being put to such a insensitive use. I presume that the person who created this was not American, probably not even Western, due to the subtitles.
Words cannot come close to describing the disrespect and flagrant carelessness with which the creator of this short is possessed.