Very credible, pick any reputed journal and you will find it stating the same points, manners may be different, but the conclusion is same.
And the most saddening part is from 4:11 to 5:32 - You gotta get out of that somehow - Media can do that.
One more thing: It is widely and rightly believed that it was indeed Gen. Mahmud who facilitated the transfer of $100K to Mohammed Atta with the help of Sheikh Omar Saeed, the blue eyed baby of Osama bin Laden. Only a documented proof is lacking, rest everything analytical and circumstantial is out there!
Widely believed by whom? Transfer of funds are not handled by Director Generals of ISI who wear multiple hats being responsible for internal/external/counter intelligence operations. There is a staff of hundreds who provide financing for various operations etc. (I do not even want to bother denying that DGISI had a hand in sending money to the perps of 9/11 attackers.) What sort of silly documented proof are you referring to? The same argument could be made by many (I am not one of the many) who believe that 9/11 was an own goal. What if an argument is made that CIA provided the money to the perps of 9/11 attacks through some middle men? What if I said the only thing missing is the documented proof of CIA Director transferring money to Atta that has not been disclosed to the public? Well your point sounds just as silly as this.
The point above is that one can speculate (which is what you are doing) so please refrain from using terms such as "widely", "rightly", "circumstantial" etc. etc.