Follow the instructions below to use the Video planes:

1. Drag in a video from Asset library to Step hierarchy.
2. This creates a plane on the scene that you can size/position where you like.
3. Select the video plane and "add selected to timeline" in the Timeline editor.
4. Click on the Timebar, then click on Video Playback.
5. Set the Timebar length to the length of the video.
6. Adjust the loop length to the length of the video.
7. Save your work.