I would like to show one video on the top half of the screen, and another video on the bottom half of the screen. I would also like to include motion in this: the top half would start to appear slowly and then take over the video completely. My objective is to make a drawing disappear by having a hand pass over it. If the camera is completely still, this could be a seamless transition.
Put one video on Video 1 and the other directly above it, on Video 2.
Apply the Crop effect on the Video 2 video and use the tools in the Applied Effects panel to crop the video as needed so that both can be seen in the video at the same time. (You may also want to change both videos' Scale settings in the Motion properties, also on the Applied Effects panel.) Then you would keyframe an animation of the Crop settings.
You don't say which version of the program you are using, but that's how you'd do it in version 11.
Thank you very much, this is exactly what I was looking for!