Canadian TV just aired an interview with one of the passengers on the flight. (Who happened to be sitting in seat 10A and supposedly witnessed the incident.)
According to this passenger the Captain exited the flight deck, leaving the cockpit door open, and tried barging into an occupied lavatory. He then ran up the aisle screaming "They're going to take us down" and urged the passengers to pray.
As he was being subdued by cabin crew and passengers he was spouting off about Al Qaeda, Afghanistan, bombs and souls.
The interviewed passenger also stated that prior to the Captain's exit from the flight deck, the aircraft was flying "erratically."
Again, this is the medja reporting so it should be taken with a large grain of salt. However, the interviewed passenger did seem sympathetic to the Captain's plight.