Earlier quoted context omitted.
Ah, the "cant happen here" argument.
Before the Internet came around, it was actively happening "here". You couldn't shop your violent extremist video around to pre-Internet mass media outlets, or if you did, you would probably be referred to law enforcement. Not all forms of this look like China, some look like the USA circa 1990.
You have no right to mass media outlets. Just as I have no right to barge into your home and force you to listen to my speech... you have no right to force the owner of a tv or radio station to broadcast your message. Your right to free speech is not a right to violently force others to deliver your message against their will... those other people have the right to free speech and liberty too.