A pane of glass in front of the camera with the image of a UFO drawn in marker, being moved by someone off frame. The shakiness of the UFO supports
this. With the poor quality of the video, this makes it even more believable, not to mention that it is all very low tech and achievable at that time.
Small disks swung from a pole close to the camera.
On the third video, you can see the pole!
Torwards the end you can see the pole on the far left of the screen. It moves to the right as the "craft" is moving right. When the pole moves left
offscreen, guess what? The disk moves left with it!