Creative Speculation

You were denying that that video was actually Osama. I provided evidence that it was.

We know for a fact that al Qaeda did 9-11: http://en.wikipedia.org/wiki/Responsibility_for_the_September_11_attacks

The FBI investigation into the attacks, codenamed operation PENTTBOM, was able to identify the 19 hijackers within days, as they made little effort to conceal their names on flight, credit card, and other records.[6] By checking flight manifests and comparing them with other information, like watch lists, customs officials were able to quickly find the names of all 19 hijackers.

Passengers and crew aboard the flights provided information about the hijackers while the hijacking was in progress. Two flight attendants on American Airlines Flight 11, Betty Ong and Madeline Amy Sweeney, contacted airline personnel on the ground. Sweeney provided the seat numbers of the hijackers, and descriptions of the men, identifying Mohamed Atta as one of the hijackers.[7][8][9] A flight attendant on United Airlines Flight 175 called a United Airlines mechanic and reported that hijackers had killed the crew.[9] While the hijacking was in progress on American Airlines Flight 77, several passengers, including a flight attendant, Renee May, contacted and reported details of the hijacking to persons on the ground.[10] Sales clerks identified two individuals to whom they sold tickets on Flight 77 as the hijackers Hani Hanjour and Majed Moqed.[9] During the hijacking of United Airlines Flight 93, Jeremy Glick identified the hijackers as Arabic-looking and carrying box-cutters.[11]

Mohamed Atta's luggage did not make the connection from his Portland flight to American Airlines Flight 11. In his suitcase, authorities found a handwritten letter in Arabic. As well, a handwritten letter was found at the crash site of United Airlines Flight 93 near Shanksville, Pennsylvania, and another in Hazmi's vehicle.[12] When examining Mohamed Atta's left-behind

Osama was more than happy to take credit for the attacks conducted by al Qaeda, which was founded by Osama himself:

http://en.wikipedia.org/wiki/Osama_bin_Laden

In the 2004 Osama bin Laden video, bin Laden abandoned his denials without retracting past statements. In it he stated he had personally directed the nineteen hijackers.[125][138] In the 18-minute tape, played on Al-Jazeera, four days before the American presidential election, bin Laden accused U.S. President George W. Bush of negligence on the hijacking of the planes on September 11.[125]

According to the tapes, bin Laden claimed he was inspired to destroy the World Trade Center after watching the destruction of towers in Lebanon by Israel during the 1982 Lebanon War.[139]

Through two other tapes aired by Al Jazeera in 2006, Osama bin Laden announced, "I am the one in charge of the nineteen brothers. [...] I was responsible for entrusting the nineteen brothers [...] with the raids" (May 23, 2006).[140] In the tapes he was seen with Ramzi bin al-Shibh, as well as two of the 9/11 hijackers, Hamza al-Ghamdi and Wail al-Shehri, as they made preparations for the attacks (videotape broadcast September 7, 2006).[141]

Identified motivations of the September 11 attacks include the support of Israel by the United States, presence of the U.S. military in the Kingdom of Saudi Arabia, and the U.S. enforcement of sanctions against Iraq.

We know what brought down the towers in detail, and we know who did it: al Qaeda.