You have to love the stop motion efforts with the aliens, and this is just the kind of movie from 1978 that can easily use a re-imagined soundtrack, which is always fun.
Billy got pushed around, and then started fighting aliens with his discovered attachment. He also appears to attack a helpless Mick Fleetwood in a van, with a beam which will dismantle him in the roadside gravel at some later moment.
A simple town girl tries to rescue Billy from cutting down everyone around him, but Billy refuses to listen. The pushing around will have a hollow and noisy conclusion in bubbling clay.