Yeah, it's normal lightning just slowed down. The charge comes down from the cloud, randomly forking and 'searching' for the easiest route down through the air (which is the first bit). Once one of the 'heads' touches the ground, you get a huge bolt of charge arcing from the ground up to the cloud, using the easy path that the first, smaller 'seeker' charge has already cleared through the air.
It all happens so fast, and the second main bolt is so bright compared to the first part that you never see the 'seeking' phase.