Chris Nicastro - Flaps were not used on take off, and yes, they were checked to be symmetrical.
On the first take-off run there was no swing, so no rudder was used to correct the heading up to the abrupt "lift off" which caught everybody by surprise. I am willing to bet any amount of money that there is no one in the world with reaction time fast enough to get the aeroplane out of the first "torque roll" (or whatever it was).
The second take-off attempt was very different, being done from the grass with the different geometry of the main undercarriage. I had to deploy the rudder almost from the get-go to maintain the heading. Again, even that we were ready for the possibility of "torque roll" due to past experiance, when it did happen, the speed of the roll left no chance for effective correction.
Jose - The swing you encounter at take-off looks nothing like my take-offs attempts. My take-off acceleration was more gradual, and the aeroplane was kept within heading in alignment of the runway all the way to the "torque roll" with no swing to the side. The "torque roll" took place further away down the runway then your lift off point (from what I can asses from the video), but I would say at what seems to be similar speed to your lift-off speed at that point (if not at faster ground speed then yours).
Cheers,
Eran