Realistically, the only institution with the power, expertise [and prior record of direct intereference] on this massive scale is the United States Federal Government. Readers may remember that shortly after the first Gulf War, media outlets attempting to bring you gory pictures of bloodied corpses on the "Highway of Death", found they were unable to do so because all of their own photographic archives had been pillaged and 'sanitized' by various federal officials.
Decoding government intent on that occasion, was as simple decoding George Bush I's intent when he banned all cameras from Dover Air Force Base in Delaware, the "secret" USAF facility used to sneak dead Americans back into the country without being seen by the public, thereby hopefully avoiding demonstrations of the sort that occurred during the Vietnam War. The entire strategy was designed to convince the American public that this was a "clean" war, where equipment got damaged occasionally, but humans never ever died. George Orwell would have been justifiably proud.
But that was then and now is now. Why would the Federal Government be happy enough to let you see the last 1,000 yards of Flight 175's approach into the World Trade Center [thousands of times over], but at the same be so obsessed with eliminating any and all film footage showing the aircraft's earlier attack profile, displayed at the top pf this page?
The most likely answer is because, as you can see, this continuous footage allows you time to study the flight profile over and over again, until you reach the inevitable conclusion that this giant and very clumsy 400,000# Airliner, is being flown with the sort of dexterity more normally associated with nimble combat aircraft. and at a very similar speed.
As any airline pilot will confirm independently, the 'reverse feel' on a Boeing 767 travelling at 575 mph is so high that the controls feel like lead, and simply cannot be moved as quickly as you see in the film without overwhelming hydraulic assistance, which can be provided only by the automatic flight director. The pilots themselves cannot disengage the 'reverse feel' placed on the controls, because it is an integrated feature designed to stop the pilots accidentally injuring passengers by imposing extreme "G" forces at high speeds.
In turn this reveals the obvious: If qualified airline captains are incapable of flying a Boeing 767 in this manner, then it is completely out of the question for a bunch of "Arab Terrorist Hijackers", who failed their basic Cessna training courses in Florida.
Put bluntly, this is the only known footage of United Airlines Flight 175 that completely destroys the government myth about 'Muslim fanatics' allegedly taking over American commercial jets. The [permissable] short clips showing Flight 175 just before impact do not allow time for such detailed analysis, but this long attack profile certainly does.
The fact that the Federal Government appears to have hunted down and captured or otherwise removed footage of this kind, does not mean that "George Bush did it". In my personal opinion he did not, and I am still entitled to a personal opinion, despite the large number of emails I receive each week suggesting that I am not.
What the evidence does suggest, perhaps even confirm, is that the Federal Government prematurely decided on a strategy, and could not suddenly throw the whole thing into reverse once they had peddled the "Osama Bin Laden did it" line. In turn this then allowed them the irresistable opportunity to impose new Communist-style restrictions on the American people as a whole, and they jumped at at. Can you name a Federal official who would not?