Tracking animated line? Video example

If you already have animations that contain position information you can tie directly to that with a simple pickwhip expression. I didn't see anything in that animation that would probably benefit from that kind of approach.

If you are using a 2 node camera, which is the default and the easiest to precisely control, one of the best approaches is to add a camera control null. Use the null to move the camera around, This will keep the camera pointed in the same direction as it moves but let you animate the position of the point of interest to point the camera directly at various elements on the screen. You can also use a point the camera at a null using a simple expression. Here's the workflow:

1. Add a 2 node camera
2. Add a null and name it Dolly or Camera Null so you can easily identify it and make it 3D
3. Hold down the Shift key and parent the Null to the Camera to snap the null to the same position as the camera
4. Immediately undo the parenting and then parent the Camera to the null so that when you move the null the camera moves
5. Animate the null and the camera moves without changing the pan or tile of the camera
6. If you are planning to also animate the center of interest and you want the perspective changes that go along with that add another null to the comp center, name it POI or center of focus, make it 3D, press P to reveal the position property
7. Select the camera and press "a" to reveal the Point of Interest property, then add this expression:

L = thisComp.layer("POI");

fromWorld(L.toWorld(L.anchorPoint));

That will build a very effective camera rig and make it very easy to track that kind of movement. If you open up at least two views you'll get the hang of creating smooth camera moves very quickly. You will end up with something like this:

One other piece of advice. If you plan on animating the position of 3D layers do that first and then move the camera. Think of it the same way you would block a scene with actors and then figure out the camera position. If you get the actors, your 3D layers, moving to the right spot to deliver their lines first then you move the camera to the right position to capture the movement it will be a lot easier than working the other way around.

If your layout is pretty flat then it might be easier to move the 3D layers in and out of the shot. You can group them using nulls so that is also easier. The most efficient workflow depends entirely on the design of the project.

I hope this helps. There are a few decent tutorials in the Overview section of this forum, and there are a few good tips ad workflows in the User Guide. You'll have to be careful to vet the folks giving most of the tutorials on YouTube because most of the new ones are presented by enthusiasts and they leave out critical information or present inefficient workflows.