Group polarization is when a group which shares similar attitudes work together towards intensifying those attitudes more than they did when they had these ideas separately as individuals. Some intensified shared ideas may be risky such as when unrulyb mob gangs comes together to push their attitudes.
Some may breed fruitful actions such as mobilising together to protect the right of animals which may save lives of many animals.
Group Polarization makes an action possible that would have been impossible if someone was standing for the idea alone, numbers increase the strength of the idea to be implemented.
Group Polarization exist in order to give strength to persuasion, the attitude of a group is improved by their number more than it would if they were standing alone.
Any extreme is bad. It is bad for a speaker to stand on the same spot without moving during his/her entire speech, and it is also bad for him/her to constantly move. The key to being effective in keeping a balance is choosing the right movements for complementing the message he/she is delivering, making the speech more authentic.