Brumby
Major
mass protest movements have a tendency to filter out its benevolent elements over time. this is because protraction foments skepticism towards moderate tactics, it is human nature to be suspicious of an approach if it does not come to fruition over time. the scary thing about mass propensity to commit violence is that it feeds on itself. some "peaceful" element will begin to withdraw out of fear of their safety, those that remain will thus become marginalized and unable to impose a check on the violence, and they will in turn fear for their safety as violence worsens. eventually you are left with a bunch of drunk and unemployed hooligans burning and looting in the name of democracy. this is what happened in Kiev, not entirely beyond the realm of possibility in HK or any protests of this caliber. how to avoid this you ask? get your points across and go home.
It is a reasonable statement of risk and hence there needs to be an end game in mind with the OC movement. Protraction carries risk.