Broadcast in the US in 1979. Sorry no video, I only recorded the audio when it was broadcast here in 1979. Part 1 is available on Youtube. The BBC broadcast this on the 25th anniversary of Panorama (1953-1978). Part 2 mostly talks about particle beam weapons. It was produced in late 1978.
Part 1 (which mostly talks about high energy lasers) is here: https://www.youtube.com/watch?v=5ma7x-paZtA