In the new editor you frame every video and image directly in the preview: move, scale, crop, mirror. That is how you get every recording cleanly into the format.
Free positioning and scaling
Select the element on the timeline. Handles appear at the corners in the preview: drag them to scale, or move the element directly to the position you want. Use the rotate icon at the bottom to rotate it.
Fit, Fill, Mirror and Crop
With an element selected, you find four options below the preview:
Fit: The whole video is visible, possibly with margins. What shows in the margins is controlled by the background in the Design tool.
Fill: The video fills the format completely and gets cropped to do so.
Mirror: The video is flipped horizontally.
Crop: You cut your own custom framing. Drag the handles and confirm with Done.
Tip: The further you zoom into a recording, the more visible the source material's quality limits become. Use high resolution material when you plan to crop heavily.