I'm not Yevhen Marchuk's fan - but he does have a point here (interview in Ukraina Kriminalnaya, in Russian, via Abdymok):

SBU and Kuchma do deserve some credit for the fact that the revolution ended without a single scratch on anyone's face. However, the main reasons were the calmness of the people and their awareness of their own strength. The organizers of the protests had conducted serious work on preventing confrontations. They were using important psychological tricks - children's songs, for example, that were broadcast publicly. I know that a serious group of psychologists worked there - it's rather difficult to keep such a huge number of people from aggression for too long.