Terrorism is the infliction and use of violence and intimidation against civilians for political aims. If those acts are conducted for political aims then they are actual terrorism.
Beating someone and torturing them while making political statements, recording it, and placing it on the Internet is thus terrorism. Rioting, trashing local establishments, and physically attacking people because of a speaker having different political views is intimidation against civilians for a political aim. This terrorism. Lighting someone’s hair on fire because she openly supports the current president is possibly an attempt to intimidate those who do and thus might be terrorism.
We should not dismiss this as “kids beating up a few people” — which we should not do under any circumstances. People beating up other people for expressing their personal political beliefs is nothing short of an attempt to silence others with violence for political aims — making it terrorism.
Is it an act of violence or intimidation? Is it politically motivated, or for a political aim? If both of these are true, it is terrorism as legally and properly defined.