Small lesson about police:
The men and women of law enforcement, for the most part, are drawn to their job not because the want to help people, or to enforce the law. They are mostly drawn to law enforcement because they get a charge out of the power that their office gives them. They enjoy being obeyed, feared, and they enjoy enforcing their demands with violence if necessary.
This is not a bad thing. Many people wish they could enforce their wishes with violence. The vast majority of police are good people who do their job the best way they know how. They are incorruptible, honest, and hard working.
In the "Don't tase me, bro!" video you saw what happens when a person does not understand what the police's job is. You had a young man who wanted to grand stand at an event. He thought that because of his right to free speech he could dominate the time of the crowd and the guest speaker. This is incorrect. The young man was not the organizer of the event. He was a member of the crowd. Even in a public building the organizer of an event has the right to expel you, a member of the crowd, from the event if you are behaving in a way that is deemed inappropriate by the organizer.
This young man was asked to give up the microphone and let the speaker respond. He chose instead to keep talking. The event organizer then asked the police to remove the young man. The police's job was clear. Remove the young man.
The police had no wish to injure, detain, or humiliate the young man. It was their job to remove him. They grabbed the young man lightly around the arms and began to escort him out. The young man resisted this escort. Very very very bad move. The police warned him that if he continued to resist he would be arrested. The young man continued to resist. In the police's minds the young man just crossed the line from someone they wanted to get out of the room and release to someone they wished to detain. Now that the intention of the police was changed from escort to arrest, they could use whatever force they deemed necessary.
The police warned the young man that if he resisted any longer they would tase him in to compliance. He resisted. They tased him, arrested him, and hauled him away.
The mistake the young man made was that he did not know what the police's job was. He believed that because he had done nothing wrong the police would not use violence, or try to detain him. This is incorrect. He believed that if he argued his case to the police they would let him go. This is incorrect. It is NOT the police's job to listen to you plead your case. It is the police's job, in part, to gather information about crimes committed, and use the State's monopoly on physical force to arrest those in violation of the law. It is the job of the Judge to hear your case. Should the Judge deem that the police did their job improperly, you now have legal avenues to claim damages from the state.
With any contact with the police, do exactly what they say, and answer any questions that pertain to who you are. DO NOT answer any questions that have to do with any commission of crime. It is their job to gather evidence to prosecute you. If they can find no evidence they will release you. If you are at a function where the police are asked to escort you out, you go with the police the very first time they ask you. Otherwise the police will use what ever force they deem necessary, including deadly force, do bring you in.
The young man should count himself luck that one of the police had a taser with them. In most places he would have gotten a few fists, or even a baton across his head.