When your music has no lyrics but your audience includes the dance-averse, a live show poses a challenge. It becomes even more of one when the show is sold-out, as with Ratatat’s Saturday-night Terminal 5 concert: The dance floor was so thick with revelers that when someone chanced a move, she had to count on everyone moving right along with her. Mike Stroud and Evan Mast compensated with lights — lots of them — and videos paired with each song. (The best of these referenced eighties artifacts like Arnold Schwarzenegger in Predator, for “Mirando,” and Paul Simon and Chevy Chase’s “You Can Call Me Al” video, for “Flynn.”) They also had a lanky, head-banging keyboardist who resembled to Animal from the Muppets. And the crowd did shake it, or at least, jump up and down. During encore “Seventeen Years” Stroud and Mast resembled silhouetted guitar gods, as people on the floor gleefully undulated and a couple of crew members and the singer for opening band Panther ran onstage to do push-ups and jumping jacks. Challenge met.