The blowback theory is not quite as nutty as the inside job theory, but it's far from sane. Remember, both Ward Churchill and Reverend Wright endorsed blowback (aka chickens coming home to roost).
Osama's fatwa against the United States did not mention exploitation of resources or people; it said not a word about slavery, wage or otherwise. The
three reasons listed (in order):
1. The stationing of US troops in Saudi Arabia.
2. The sanctions regime against Iraq.
3. US support for Israel.
You can argue that 2 and 3 are blowback for oppression. The obvious problem is that none of the hijackers and none of the major leaders of al Qaeda were Iraqi or Palestinian, while a large number of both were Saudi nationals.
Looked at with a critical eye, the obvious conclusion is that 1 was the main reason for the 9-11 (and embassy) attacks, and the reason that rankled was not oppression but religious fundamentalism. The presence of US troops on sacred soil was seen as offensive to Allah.
It is also hard to argue that a lot of the guys involved in the planning and operation of the 9-11 attacks were truly oppressed. Bin Laden was the son of a billionaire contractor, al-Zawahiri was a surgeon as was his father, Atta was the son of a lawyer, Ziad Jarrah was born into a wealthy family.
As for the video, holy crap 3.5 hours? No way.