Thanks alot, I will try that out. (I did allready recognize that the Blend did change from 1 to 0 at some point, but didn't know what to make of it.)

But the animation after that seems still a bit too tricky. It cannot really be the case that they adjusted all those numerous keyframes by hand, or not?
Such jumpy movement over multiple seconds would require insane amounts of input to look good at the end (mainly due to high revision and retweaking work). It's like making a 3d motion path by hand + velocity and inertia information.