Spoilers obviously
Part 1:
Part 2:
Part 3:

I am counted amongst his subscribers. Preston's gift is his ability to make great leaps of faith while talking in a fast monotone. You never notice that his theories have a lot of air where there should be strong foundations. Nevertheless, I like what he says so I listen.

What exactly is this? A book spoiler or a theory like R+L=J? I'm a show watcher... is this something I want to see?

Don't watch it. It reveals some of the mysteries like the death of Jon Arryn (Ned's predecessor at hand).

Is this the Lannister Honeypot guy?

Interesting, though like was said, there's a lot of compounded leaps of faith. I am impressed with his ability to support most of his assertions with some kind of excerpt, even if some of them are still a bit of a stretch as far as what he took from them.

I wouldn't call any of that a spoiler. I watched parts 1 and 2 and it seems like speculation for why little finger has done some of the things he has done, mostly supported by excerpts. I am a tv watcher and I'd say this is more based on the books. I've watched seasons 1-4 twice and I certainly couldn't come close to mapping where families live like this guy can. Multiple families he mentioned I had never heard of (Hightower, Florentine, Tarly?, several around the vail, etc).

Also, he said he thinks either Robert or Joffrey tried to have Bran killed with the dagger. Why would that be true? Seems it was either Jamie or Cersie?

In one of Tyrions chapters he thinks something to the effect of "killing bran is a move only someone with a dull mind would attempt...duh Joffrey. I humiliated the prince for not observing courtesies and in turn he hired a sellsword and handed him a valyrian dagger."

And yes, the stuff about who killed Jon Arryn and Varys other king are kinda spoilery.

When you have a hard time distinguishing between fact and speculation, it's hard to say that it's a spoiler, it's certainly not a spoiler that ruins anything material in my mind.

Firstly, Tyrions revelation was better constructed and its a eureka I figured it out moment for Tyrion.

And that is probably the most concrete explanation for Bran's assassination GRRM will give us. Unless Cersei confesses to the High Scepton, Tyrion is the only POV character smart enough to piece it together.