The entire idea of movement in climbing revolves around moving from one body position to the next. Knowing that it's more of a gradient rather than a binary concept, let's quickly look at the two main types of movement:
In more static climbing, a climber uses the holds they have to move comfortably into a body position where they are ready to change to the next hold. Examples of this might be perching weight on a good foothold before moving the hands, finding balance on one leg before stepping up to the next foothold, and locking off on one arm to move the other hand.
More dynamic climbing revolves around the climber making similar movements, but with momentum. A lockoff made dynamic might involve a lot more motion coming from the leg and hip, rather than the arm and shoulder. Especially on steep walls, and for very large moves, the ability to create and control momentum becomes crucial.
However, in these dynamic movements, the thesis I started with remains true. A dynamic movement is simply using momentum to move from one body position to the next, rather than tension. There are many applications of forced dynamic movement: most notably, larger upward movement becomes possible. Lateral movement can be added in to spice things up. Dynamic movement to poor holds can require immediate resistance ("holding the swing") rather than the constant tension offered by static resistance climbing.
Lately, I was inspired by a post on Facebook to think about how we can use body position planning to add rotation to dynamic movement. If the target holds require the climber to be in an externally rotated position, a twist is added into the dynamic movement. If the movement is also large enough to require a foot-cut, that twist becomes a full body rotation. In many cases, like Sharma's beta used here on Evilution, this is just enough rotation to get the body underneath the target hold. (Perhaps not the best beta, but we're just examining movement here.)
Moving B laterally will make rotation more or less evident.
Moving from A to B isn't a lateral movement, but requires rotation to get underneath B and grab it from a proper angle. Failure to do so would keep the climber from being able to weight the hold. The climber starts facing slightly right, but close to the wall, and ends facing straight rightward. In this case, when I say "the climber," I really mean "the climber's hips," because that's where the rotation is evident. The starting position will have the hips square to the wall, and in the finishing position they're facing nearly horizontal, with the direction of movement. Watch that video again and watch Sharma's hips to see what I mean.
It is also possible to rotate past 90 degrees. The big boy beta on Toxic Avenger (not a great angle, but you get the gist) involves a dynamic move that sends the climber from almost fully laid back facing left to facing right and almost away from the boulder.
Notably, Toxic Avenger climbs out of the opposite terrain (exiting a roof, rather than entering one) - this setup would present much less difficulty.
In this case, moving from A to B requires a much larger rotation, as the climber would start facing left. Again, the rotation is evident in the climber's hips. The starting body position will be nearly square to the wall, but the end position (before swinging the feet back on) will have the hips facing outward, in this case opposite the direction the climber moved.
That's all for now. And yes.. I do love responding to these kinds of questions on Facebook. Thanks for commenting, Aaron!