The B-Twist is an advanced breakdance flip which takes a lot of practice to perfect, as shown on the show. The move consists of the performer rotating in a horizontal position. This is similar to the Butterfly Kick (which has been performed on The Next Step) but rather than kicking, one twists at a fast speed.
The B-Twist has been performed in many routines; Eldon mentions it and performs it in an episode in the middle of Season 1. It is revealed near the end of Season 2—to the surprise of many of his fellow dancers, since Eldon, West, and Hunter can perform it without fail—that James has trouble performing the move; he is advised by Luther Brown only to perform it when he hears it "talking" to him.
At Nationals, James is torn between performing the B-Twist in the "Never Get Lost" small group routine or not; he ultimately doesn't, slightly disappointing the rest of A-Troupe. However, after being encouraged by Riley, he aces it in their "Whirlwind" duet, exciting the rest of the team.