Blending Two Shots for Continuity I have been watching Zach King videos on YouTube (the Vine magic guy) and I'm curious how to edit two shots together so that body movements stay the same, yet an element is brought into the shot.  I'm ot even sure what the name for this is.

An example is in the link below.  In the first two Vine videos starting at 3:03, he clearly meshes two shots together somehow but the placement of his body stays consistent.  Immediately after, he makes it appear as if he pulled a cat out of his computer screen (again, obviously two shots) but his body movements stay consistent.
Very easy to do, well theoretically.  On cut actor freezes his body, friends places the prop - in this instance the cat, on action the actor continues his movement.  The quicker and non intrusive the introduction of the prop, the less movement the actor will have and the more seamless the cut will look.

The main thing to remember here is to be prepared to have a lot of takes.. it will take time to get it right.