How to know a community of researchers in order to be more successful in research and getting papers accepted? Knowledge is what lies between heads of people in a community; This is an idea, I recently learned from a video tutorial on writing research papers in a youtube video. In this video, a professor presents such a model of knowledge which is different from what I already thought. 

This suggests a measure of success in research is the amount of change she's able to effect in the space between heads. This video talks about community and people in power in that community. So we must know the community, its structure, who the people in power in the community are, and what knowledge is already in the space between heads. 

The ideas proposed in this video seem tantalizing but I feel I haven't completely understood his thesis.  I will try to lay out what's hanging me up about this: 

I want to understand what a "journal's community" is? since this professor says that will affect the acceptance of a submission. 
In short, please help me understand the outlined aspects of this model of knowledge?
Note from question editor: if you have some ideas about how to improve this post further, with the goal of getting it reopened, please grab your red pen and help out.  Thanks.

We usually want to know something from a perspective. Here we want to know a community such that we as researchers can better understand how to communicate with the community through Papers. All of the aforementioned sub-questions are around this single thread.
1) Communities usually revolve around research topics, rather than journals. There are smaller and broader communities. The smallest ones are about a very specialized topic that only three research groups in the world are knowledgable about. The broadest ones are about an entire overarching research field. Of course, there also are overlaps between communities.

2+3) In my field, the only correct answer would be: Go to meetings and conferences. This is the place where people go to exchange ideas, in talks and informal conversations.

4) This is a very broad question. There can be all kinds of relations between communities, personal ones (overlaps) and emotional ones (respect, envy, disregard).