(since you want it animated) 
//primitive wrangle int primpts[] = primpoints(0,@primnum); removepoint(0,primpts[-1]);
PhiiLLThomasRunning
To avoid weird normals with boolean, both the original geometry and the cutting geometry needs vertex normals. It seems like in this video he is not cutting it live, but have separated the geometry first and then render one of them with opacity. Some renders like Vray and Arnold can do this in rendertime.
I guess you are right, with the seperation bevorehand. But how did he make this smooth opening cut, which reveals the inner parts?
Could it be an exported animation from a CAD software?
//set this in a primitive wrangle and connect your geo to transfer from to input 2
int primid;
vector uv;
xyzdist(1,@P,primid,uv);
@Cd = prim(1,“Cd”,primid);