Help Wanted!

I received an e-mail the other day from a reader in Germany, who wanted my help in identifying a sci-fi movie that he remembered from the 70s. Since I haven't been able to help him, I thought I'd post his query here, and see if any of you guys out there could identify the film/show he remembers:

Hi there Christopher,

I am writing to you from Germany and was wondering wether you could help me find a movie that I have been looking for - for, literally, ages.

One scene has stuck in my mind since childhood and has seen me scouring the web for an answer as to it's origins.
I don't recall at all what the story of the movie in general was about. It aired here in Germany during the late seventies and all I remember was that it was profoundly gripping and terrifying.

This is the scene that I remember:
The film was set in a strange future world, where two people were stuck in a hilly desolate landscape. The sun was setting and the rolling hills were lit by the late afternoon twilight.
The two characters were talking urgently and needed to get away from that spot to evade an 'enemy' or alien force, which was closing in on them. This 'enemy' had begun to appear on a broad front over a ridge behind our heroes. They were silver or white and had an egg-shaped or balloon-like appearance. There might have been ten or twenty of these creatures, which moved along in a nightmarish bouncing slow motion dance.
The balloon creatures could have been bobbing down the slope toward the sunset. The two heroes might have been near a shuttle-like vehicle.

Thank you ever so much for your time!

So, does this sound familiar to anyone out there?