FKA Twigs knows how to work a stage, as Vulture learned firsthand back in May. So for her latest turn in BBC Radio 1’s Live Lounge, she didn’t simply show up to sing a pop hit; she showed out. She performed a swaggering, guitar-driven take on Sia’s “Elastic Heart,†complete with original choreography and a backup dancer, which goes beyond what most other artists bring to the lounge. Needless to say, she set the bar high for everyone else who’ll have to step into the BBC Radio 1 booth after her.