There are two ways for you to add a video layer (PiP) to the canvas (the same as adding an image layer).
First, go to the Media or Stock section and click the Add as Layer button at the bottom-left corner of the video to add it as a layer.
Second, drag and drop the video to the center of the canvas directly.
Currently, you can add unlimited video layers to a scene. However, adding multiple video layers may cause instability problems. So, we recommend using computers with 8GB+ RAM to create projects with multiple video layers.