The actor's name is Georges Descrieres.
Not sure of the movie. Would guess "Two for the road" 1967?

And yes it is a C800, famous glider in France in the 50's before the
arrival of the Wassmer "Bijave" in 1965. I soloed in the Bijave but
remember seeing a C800 on the wall of the hangar of the soaring club I
was flying 30 years ago...

Richard
ASW19
Phoenix AZ