By Way Of
Why do people say that? what is the meaning of this?
So the person in your example would live in New York and be born in Los Angeles.
He came to live in New York while living in Los Angeles.
Through is synonymous with: by, by, and through.
I met Emma through Andrew.
He traveled to Paris by cane.
Such a thing.
This (via Los Angeles) means he is from Los Angeles and now lives in New York.