The crossover turn is a sideways flip turn. An earlier blog post featured videos of this turn done by Eric Shanteau and a slo-mo step by step video.
Ariana Kukors is the 200IM world record holder. She and the other Olympians are using this turn for back to breast. We introduced this turn several years ago at the swim club and the high school and while many were intrigued by its efficiency and beauty, no one has persistently practiced it enough to use it in racing. It is faster than the traditional open turn by at least .3 seconds, about the same difference as the freestyle flip turn is faster than an open turn at the wall. All of us do freestyle flip turns. We learned to do it by practicing it over and over. Same with this IM turn. Anyone can do this turn with enough practice.
