“We dance in the streets because we don’t have anywhere to go now.” There is much that sticks and stutters and loops in the mind after watching “Dark City Beneath the Beat,” a bright, ebullient and simultaneously seething musical documentary dedicated to the Baltimore club scene, but that’s the line that lingers longest. An apparent expression of joy, chased by an admission of crushing, unequal reality, it’s said matter-of-factly by a young black choreographer trying to keep art alive in the face of diminished creative space. It distils the push-pull impulses of TT The Artist’s unique film, which mixes and remixes fluorescently staged performance and candid sidewalk-level vérité to offer an abstract history of a city’s rich musical subculture, a busy snapshot of the black community in which it flourishes, and a consciousness-raising statement of resistance against political and economic oppressors. All that in 65 minutes, and the beat never lets up once.