Voldar: very instructive video.
I am not speaking from my own experience with TCS -- but rather, I refer to the experience that early 2011 model year Ford Fiesta owners have been having.
Ford offered the Fiesta, in its 1st and 2nd iterations (of model year 2011) without the ability to turn off the TCS system. They then offered the car, in its third iteration of Body Control Module -- with the ability, thru the interactive screen, to turn off the TCS system.
The reason they did this, is 'cause a sizable contingent of owners found that on glare ice, the car simply would not move, despite the throttle being pushed gently, or being pushed fully, or whatever. So, when cars would encounter ice in the middle of an intersection (once the driver decided that he had enough car-space / safety margin to proceed to cross the intersection) - they would simply stop dead in their tracks. No response to the throttle. They felt like they were "sitting ducks"! Now, granted, the conditions were very icy. And in many of the cases, the people had just the OEM all-season radials, rather than all-weather tires (better) or winter tires (better yet) or ice-optimized winter tires (best).
However, quitei a few found it to be very, very bad.
I suspect it was how Ford calibrates the TCS.
The same did not seem to occur in the video, with the Bosch-developed TCS.
I note that the 2012 Mazda 3 has a dash-board-selected TCS-off / ESC-off combination switch. The owners manual has a section in it, that indicates the conditions under which the switch should be actuated.
The Focus has the ability, in 3 of the 4 trim lines, to turn-off the TCS (but not the ESC). They undoubtedly have this in place (as they now have this in place for the Fiesta) for a reason!
Incidentally, in order (in the S Model Focus) to momentarily cancel out the TCS -- all a person needs to do is rig an interrupt switch, to any of the ABS sensor wires to any one of the wheels. Actuating the switch will kill the system; moving the switch back to original position will (with about a 20 second delay) restore normal action.
The problem is that this switch will simultaneously kill the TCS, the ESC, and the ABS all at the same time. It is very hard (some say, well-nigh impossible) to rig an arrangement to only kill the TCS or to only kill the TCS and ESC (and not the ABS) unless you know how to break into the encrypted software, and you know how to code!