I have a deep personal interest in this issue. My dad's family settled in Allegheny County before the Revolutionary War. I suspect much of the divide is centered on geography. The capital of Annapolis is an abstraction in Allegheny County. When I lived there in the 50's Ralph Kiner of the Pittsburgh Pirates was every kid's hero. Taverns served Pittsburgh beers and only Pittsburgh television was accessible. Men went to Charleston, West Virginia when they need a job not Baltimore or Annapolis.
One fact this video omits is that these counties are mineral rich while the downstate effete are imbued with drippy environmentalism and fears of global warming. Only Allegheny and Garrett counties have natural gas and oil that could be exploited through fracking but in an effort to save the good simple souls who live there from themselves Maryland outlawed fracking.