First, use all the clips in your timeline (in this case he uses three clips), make sure they’re the same length, and stack them on top of each other. Next, we learn how to create the uneven split screen that we see at the beginning of the video. You can change the width, color, and shape all within the Title tool window. The rest is as easy as choosing the line tool, drawing a line between the clips, and then customizing the line however you see fit. To add a different colored bar between the screens, add a Title to your project. Once you’ve done this, you’ll be able to drag the clip on top to the left or right - and vise versa for the clip underneath (on your timeline). To do this, you’ll see the Position option under “Video Effects.” This will allow you to drag the clip around the preview window as much as you’d like. Since each clip is full sized, you’ll need to crop the left and the right side of each clip by 25 percent, so go to Video Effects > Transform > Crop and then enter 25 for the left and right.
Once you’ve cut the clips down to two individual clips of the same length, stack the second clip on top of the first. For a vertical two-screen split, take your two individual clips and create a new sequence.