Create a split-screen effect in iMovie on Mac
You can connect a clip to another clip so that both clips play at the same time, using a split-screen effect. You can also select whether the connected clip appears in the left, right, top, or bottom of the frame, and whether the connected clip slides into the frame. If you add a slide-in transition, you can set its duration.
Create a split-screen clip
When you see the green Add icon (+), release the mouse button.
If the video overlay controls aren’t shown, click the Video Overlay Settings button.
Click the pop-up menu on the left and choose Split Screen.
The split-screen controls appear above the viewer, and cropped versions of both clips appear in the viewer.
To change when the split-screen effect appears, drag the split-screen clip in the timeline so that it connects to a different spot in the clip below, or drag it to a different clip. You can also drag the ends to lengthen or shorten it.
To apply the change, click the Apply button in the split-screen controls.
Adjust a split-screen clip
In the iMovie app on your Mac, select a split-screen clip in the timeline.
If the split-screen controls aren’t shown, click the Video Overlay Settings button.
Do any of the following:
Set where the connected clip appears in the frame: Click the Position pop-up menu and choose an option.
Add a slide-in transition and set its duration: Drag the Slide slider.
If the transition duration is set to zero, no transition appears.
To apply the changes, click the Apply button in the split-screen controls.