If I understand the prelim report correctly, it just says that the autothrottle was engaged. It does not specifically state that the autopilot was engaged. Not that it really matters.
My question to B777 pilots ONLY (If you are not rated on the B777, this question is NOT to be answered by you):
Could you explain to a non-autothrottle (CRJ) pilot the differences in short term and long term effects of physically moving the thrust levers with the A/T engaged. Does it
1. Disengage A/T?
2. Cause an immediate thrust change which is then gradually changed back to what the A/T thinks it should be?
3. Stay at the manually commanded thrust for x time?