Hello, all!  Very simple edit here.  I'm flopping a shot of someone whose shoulder is cutoff on the right side.  However, it's a high contrast b&w shot and I can get away with using his left shoulder to fix the problem.  I was imagining I'd crop the flopped show and thus expose the shoulder underneath the video track with the flopped shot (using some resizing effects to line it up properly).  My basica question is how can I expose a video layer or frame that is essentially underneath another video frame?

You'll need to use the "Animatte" effect in the key group. Use the "poly" tool from the wireframe tool column to draw a cut-out for the shoulder, and do it on V2 with your flopped shot on V1. You'll need to ALT drag a flop effect on top of the Animatte.

Cropping a shot using the 3D warp effect, reveals the shot that's underneath.

Euchrow:

Cropping a shot using the 3D warp effect, reveals the shot that's underneath.

Although this is correct, I think the point of Larry's suggestion is that the area that will become "transparent" can be shaped to fit the shape of the shoulder.
The 3D warp is only going to be adjustable horizontally or verically (or both) - but not angled or curved.

Regards,
Douglas

Maybe, but since the OP stated that he doesn't know how to 'expose a video layer that's underneath' it's good for him to know how to do some basic cropping and resizing.

Problem with the Animatte is that although you can move the Mask, you can't move the cropped imaged from within the Animatte. So he would probably need to put an extra resize or 3D warp nested inside the Animatte to align both shots. Which then again makes the solution maybe more complicated than necessary.

Here is a video tutorial, in which I explain the use of the Animatte in a way that might be useful in this case.

The object of the Tutorial was to answer a completely different post a few years ago, but it should still be reasonably relevant.

I have also a little more about controlling the splines and their anchor points in this Tutorial

Regards,
Douglas

Thank you, everyone!  I'm able to use the 3D warp to make this simple fix but I'll be moving onto learning the Animatte effect ASAP.  This was a very helpful experience!