Protest is a valid form of action in a democracy, over time people get fed up with the Government refusing to listen to peaceful protests and eventually people become frustrated and the protests become more and more violent, but overall I think that protesting is a extension of a democracy and is needed.
I think the protests in Venezuela are a result of a failing democracy. The things in that country are falling apart and have been falling apart for years. Even when Chavez was still in power. Now that he is gone, things are getting even worse and the problems are increasing.
A healthy democracy is one that is governed by the people, for the people. In a representative government, citizens debate and decide their views on important public policy issues. In turn, political leaders are responsible for fulfilling the wishes of their constituents. Peaceful public protests are important vessels for furthering a cause or raising awareness of gaps in legislation. However, extreme protests such as those in Venezuela suggest that democracy has failed. When violence or radical protests are necessary for the people to be heard, it implies that lawmakers are ignoring citizens' concerns, leading them to lash out in response. If the Venezuelan government was more proactive and attentive to the needs of its people, such extreme acts of rebellion by the people would not be necessary.
I do not believe extreme protests such as those in Venezuela are an extension of a healthy democracy. These protests are the result of failure. When that many people can disagree with a government with so much fervor that it comes to that point of civil unrest, it's clear their voices have not been heard.
Extreme protests are harmful for countries because they prove the government is out of touch with the general population. Usually these governments are communist regimes that do not respect the rights of the people. The citizens are lashing out and trying to gain the respect of the government by causing problems.