Infinite zoom effect

Unfortunately, that is not a very good tutorial and the workflow isn't very efficient. Following along with the steps the presenter proposes this is a much more efficient workflow

• At 1:40 - it is more efficient to open the footage in the footage in the Footage Panel and set the in and out points you want before creating a comp. Then all you have to do is create a new comp from the trimmed footage
• At 1:48 - centering a point of interest is easier if you use the Pan Behind/Anchor Point tool to drag the anchor point of the layer to the center of the point of interest in the shot, then reset the position property. It would be a good idea to add a layer marker at that critical point
• The freeze-frame isn't necessary if the shot is motion stabilized or it is shot with a moving camera. Freezing the frame is OK for this shot but it should be done on a copy of the footage instead of the original footage. The efficient workflow would be to motion stabilize a copy of the footage layer so you could keep the motion in the shot and still do the effect
• At 3:45 all you have to do when creating the mask is set the first point, press the letter s to turn the mask into a subtraction mask, and then complete the mask. You can press the Stool at any point as long as you have the path selected. This is way more efficient than going through all of the steps to invert the mask or change it to subtract
• At 5:22 - Duplicating and moving the layers would be a lot easier if the anchor point had been properly set up in the first place. I would have then just added a simple expression that offset the layer below by a fixed amount by using Index -1 instead of the layer name in the position and a simple expression like this:

  mstrLyr = thisComp.layer("Master");
  multFactor = index - mstrLyr.index;
  ofst = 1000; // z offset per layer;
  [mstrLyr.position[0], mstrLyr.position[1], mstrLyr.position[2] + (multFactor * ofst)]

• "Master" would be the name of the first layer with the mask. All others would be below the master mask and you could duplicate them as many times as you like and each would move away from the "Master" layer by 1000 pixels in Z. If the "Master" layer was on the bottom of the stack, each duplicate would be closer to the camera by 1000 pixels. If you move the master layer all of the other masked layers would move with it and stay aligned
• Animating the camera could also be a lot easier. All you have to do if you have things lined up and centered properly is move down the timeline, select the Z value for camera position, hold down the shift key to move quicker, and drag the Z value in the timeline to move the camera into the scene.

If your layers are all stacked up in the same position then you did not offset them or the focal length on your camera is way too long. Make sure you vet your trainers. The presenter for this tutorial is an enthusiast, not a pro, and the workflow and the explanation are all quite amateurish.