Thought I'd clear it up for people:

The short answer is his people are indeed from Ulster, from County Antrim, Ireland. They left from Coleraine town circa 1719 and appear on the border of the Pennsylvania and Maryland Colony in the early 1720s. His immigrant ancestor was named Alexander McKean and yes, the two lads who run the Ulster Heritage DNA Project are from the same McCain family.

The long answer can be found here.

I can't get a handle on O'Bama though.