Jin Trapped in Weird Sideways "Seinfeld" Universe

This is just an excellent find. But what does it mean? Has Jin gone back in time, switched places with Jack, and moved to New York in the late '90s? Is Kramer Jacob? SO MANY QUESTIONS.

(Note that in last week's Hurley-centric episode, there was a reference to "the Human Fund." The pieces are all falling into place.)