I've Made a Video about Anarchism

[Anomalocaris]

The whole Everyone being armed, second-amendment-being-protection-against-organized-tyranny is fundamentally laughable.

Well, I'm happy that you're amused--But that's not what I was actually suggesting though.

I was responding to your specific claim that any and all attempts to re-establish governance or impose tyranny would be limited to militia members. 
What I was suggesting was that such a threat could come from virtually any group of individuals not on board with the notion of anarchism; Including, but not limited to, staunch conservatives, religious fundamentalists, Marxists, ethno-nationalists, ex-military...Hell, even ordinary folks who may have just miss having a Constitution and flag to pledge allegiance to could conceivably attempt to organize and implement their preferred brand of law and order. And that they would undoubtedly be armed--as most anyone living in an anarchic society would be.

I wasn't making the case for anarchist society being a realistic possibility. I was simply musing on a hypothetical scenario in which such a society would already exist.

An armed but relatively untrained and unorganized mob tends to self-eliminate through klutzy fratricide if its arms are called upon. An organized and even partially trained armed organization would be a match for an unorganized and untrained armed mob many times its own size.

So in the anarchic world, a thinking person with a mind for power grab will focus on creating or coopting the only organized armed body in its community.

Your assertion hinges on the assumption that everyone with the mind to make a power grab is a thinking person and that thinking people with the mind to make a grab are immune to overestimating their own strengths and capabilities, though. Neither of which is really the case.

So could a thinking person successfully co-opt a militia of anarchist True Believers and bend them to his/her will of reimposing government tyranny? Uh...Sure, I suppose. Lol
It seems far more likely that they would seek to organize a coalition of like-minded individuals and perhaps enlist the aid of some of those ex-military types I mentioned earlier though.

Not everyone who grabs for power will be a thinking person.  In fact most won’t.   But the notion that somehow all the amphibious power hungry types, both thinking and non-thinking, would just miraculous cancel eachother out, and anarchist society will somehow remain free of tyranny, is totally contrary to every historic instances when things began to appear to evolve in that direction.

What will by far be the most likely to happen in a anarchist free for all is most of the ambitious power hungry types will be baffoons and become road kills, as the few most capable of cold observation, cunning stratagem and ruthlessly calculation bubble to the top. Chances are eventually a figure like Napoleon, or Attila the Hun, or Genghis khan, will assert dictatorship after a period of multi-sided civil war,  and from there he will consolidate his position by swallowing up other communities that do not yet have a authority of command and control to rival him.     And it will turn out most of the most laquaciously freedom loving will be the exact ones who will also be the most laquaciously grateful for the stabilizing the glory bestowing tyranny.   Just look at the Republican Party to see how, to those who believe in free for all, how powerful love of freedom sounds, and how worthless it actually turns out to be when put to the test.