For its annual holiday concerts of cherished music from the early music repertoire, Folger Consort presents an intimate program revisiting its beloved album, “A Medieval Christmas.” The generously resonant nave of St. Mark’s on Capitol Hill provides the ideal acoustical backdrop for harmonious and joyful early music for the Yuletide season. Performances also available at 8 p.m. on Friday, December 17 and Saturday, December 18.