Their claim is Bush set explosives in the buildings even claiming you could see the windows blow out from the explosives as the buildings came down.
To believe this monumental piece of nonsense you would have to believe a conspiracy so HUGE and far reaching as as close to impossible as is possible. Have you any idea the thousands of people involved in the investigation of the tragedy? No way can that many people keep a secret such as you seem to be implying was done.
As for the windows blowing out. A fire inside a house or other building without a collapse can blow windows out just as extreme heat without a fire can blow the windows out of a closed up car on an extremely hot day. Plus as the buildings compressed (collapsed) the downward force caused the windows to blow outward as the atmosphere inside the bldgs was forced outward by pressure.