- Open the Cross Section window
on the left sidebar. - Activate the Plane checkbox and press Create to create a default clip plane. The generated plane will appear as an item in the Object List.
- Select the plane item in the Object List and configure its Object Attributes.
- Use manipulators to change the position and orientation of the plane.
- Press Animate > Insert keyframe (Shortcut: I) to insert the first keyframe.
- Left-click and drag the timeline indicator to a new timestamp (optionally press & hold SHIFT to snap to the ruler lines).
- Move the plane using manipulators.
- Insert a second keyframe.
- Repeat steps 6-8 as many times as desired.
- Optionally, select a camera and add keyframes for it.
- Adjust animation range so that it covers all keyframes in the scene (keyframes of the plane and the camera in this case).
- Click
to move the timeline indicator to the start of the animation range, and click 
to preview the animation. - Press Export and render the video.