It's not so much about African-Americans starting their own separate, insular economy though. It's about using the power African-Americans have as consumers to increase the economic standing of their neighbourhoods. The idea isn't that black people living in a suburb in Connecticut should seek out other black people to buy from. It's that businesses in African-American neighbourhoods are primarily owned by Asian immigrants, or are chain stores where the majority of the profit goes to rich investors who- whether black or white- do not live in African-American neighbourhoods and whose profiting presents the black community with a net gain of zero.
In simplistic terms, if African-Americans open up small businesses in their neighbourhoods, run by people who live in the neighbourhood, the profit of the business owners goes back into the local economy. It also presents increased employment opportunity because the locals can be free of discriminatory hiring policies and demand for culturally-biased qualifications like SAT scores and college degrees, which in all honesty are nothing but symbolic capital. More money means more taxes and therefore more servicing from the public sector; less crime means more servicing from the private sector.
Even if the rhetoric is all "those white devils want your cash; give to your black-brothers!" the idea is a fundamentally good one, and it's still, at its core, a strategy of integration.
What you are describing is not at all what this guy is describing. What you are describing is far more reasonable.
This guy is saying that black people should not buy at any business other than one that is owned by a black person, IE, if the 7-11 down the street has a white cashier, you should not shop there. "What is wrong with that?"
I agree with you Melchior that there are some elements of helpful things in the concept over all (Not Reaper's concept)
What he is describing, however, is limiting and tailoring your business entirely to black people. I don't know any businessman that would want to limit his customer base in this manner and I do not know how it would help make anyone better off than they already are.
For example , I mentioned a Jamaican market I shop at earlier. Almost everyone that shops there is black. I give them my money all the time. They send money back to Jamaica. Would their business be any better off if there was a sign on the door that said "Only black people allowed?"
EDIT: Outside of skin products and beauty products for black women, i'm struggling to think of ANY business or product that needs to be dedicated to black people alone. We are all humans and all need the same things.
Take Reaper's previous example of FUBU. This first came out when I was in high school, I know for a fact it was extremely popular with a certain segment of white people, and with Hispanics in general as well. This company still folded. Imagine if they sold it only to black people.