Reply #1: Very interesting, I hadn't heard of this. I found a peculiar article

[greyl]

from 2003:

Journalists commonly attribute the murder either to al Qaeda or to the Taliban. {2} That seems logical enough. Massoud's United Front was fighting a war against the Taliban at the time. The Taliban were in turn protecting al Qaeda, an organization blamed for a number of sophisticated terrorist attacks, including those on 9/11. Simple as these explanations may be, Massoud's murder has never been solved. The details of the assassination, which included an explosive charge disguised as a battery pack for a video camera, the acquisition of stolen passports, and the death of both assassins, at different times and by different means -- suggest a sophisticated conspiracy. Dead men tell no tales, and in this case, neither have the living. The Taliban, for their part, have denied any involvement in Massoud's death.
http://www.ratical.org/ratville/CAH/

edit: highlighting quote from article in OP:

described how al-Qaida staged the killing — two days before the Sept. 11 attack on America — hoping to strike a fatal blow to the pro-U.S. Northern Alliance.