I'd like to say first that my comments below are not about Systema itself (I don't know enough about it), rather about the video clips themselves.
3 thoughts.
1. The attackers go down so easily that it lacks credibility as a demonstration. In the stick attack video, for example, much of the disarming technique can be simply boiled down to a) dodge the stick, followed by b) push the attacker down. A little too simple. I'm watching it thinking "no way a real attacker is going down like that." And in some of the others, he starts going down before he's even forced in that direction.
2. I understand why the law enforcement guy before was critical of the car-knife video. It seems unlikely that this would have a high rate of success. For starters, in the first demo of the video, the blade of the knife gets pushed into the underside of the defender's wrist. This is obviously very bad. The point being that when under controlled response from the attacker in a demonstration a cut is suffered, how reliable can this particular technique be under real circumstances? Notice that I'm only criticizing this 1 technique here.
3. The article about taking punches was pretty good, mainly the part at the bottom about breathing. This is important for any martial artist.
Systema is most likely a very good martial art. My comments should not be interpreted as an endictment of the art. Regardless of my impressions, I think these are good to show the general idea behind Sytema.
