Hello,
I am having exactly the same problem. I would be thankful if someone could tell me where am I going wrong or solution to it. The code I am using is :

void setup() {
 size(640, 480, P3D);
 background(0);
 // Load and play the video in a loop
 
 
  myMovie1 = new Movie(this, "boyonbike.mov");
  myMovie1.loop();

  myMovie2 = new Movie(this, "littleboy.mov");
  myMovie2.loop();
 
  frameRate(30);

}

void movieEvent(Movie myMovie) {
     myMovie.read();
}

void draw() {
 //tint(255, 20);
 if(tag == 0)
 {
   myMovie1.loop();  
   image(myMovie1, myMovie1.width, myMovie1.height);
 }
 else if (tag == 1)
 {
     image(myMovie2, myMovie2.width, myMovie2.height);
 }
}

I am setting the tag value in rest of the code. The problem is that it plays the video properly according the the tag values, but the sound associated with it is not played continuously , but is played only for the initial 2 seconds. I want the sound also to loop with the video. Can anyone help ?

Thanks so much!