Just FYI, the extra collective requirement in nose-down tic-tocs is a result of the tail boom (and all the weight of the tail assembly) being above the pivot point of the tic-toc rather than below. In nose-up tic-tics, where the tail is down, the pivot point of the tic-toc is very close to the tail and thus the tail need not move much (which in turn means it has less velocity, less momentum, and carries far less kinetic energy). In inverted tic-tocs, the tail boom and tail blades are well above the pivot point and thus must be moved in a much larger arc, giving them greater momentum and kinetic energy that the cyclic and collective pitch must overcome in order to swing them to and fro. Making matters worse is that unlike nose-up tic-tocs (which represent a class-1 lever), inverted tic-tocs create a class-3 lever system, which means that the weight being rotated around the pivot point is further away from the fulcrum than the force (eg main blades) driving the rotation. The weight of the tail assembly has a mechanical advantage over the main rotor. Hence, more force is required from the main rotor, and thus more throttle/collective and cyclic pitch changes. Even though the helicopter is balanced front-to-back with respect to the main shaft, rotational physics changes the properties of the front vs the back of the heli.
About the 5:45 part of the aerodynamics, There is more rotating inertia because you have the tail swinging back and forth. same with tail left tictocs are easier and can be done faster than tail right tictocs(side tictocs that is) because the tailrotor, keeping the tail steady is also pushing the helicopter UP.
perfekt, you know how to do it. On 5:40: learning "simple" tail down tic tocs is funny, I am lightyears from doing this :-) How long did you flying to get those skills ?