Definitely shot on video. The exception being the film clips from Star Wars and the Boba Fett cartoon.

I'm amazed it was converted to PAL. PAL to NTSC seems to have worked pretty well back then, but the other way around seems to have been problematic well into the 80's. I read somewhere Dallas went back to editing episodes on film as the show was very popular in the UK, and the NTSC to PAL conversions looked pretty bad on tv there.

IIRC, it took a while before Star Trek TNG aired overseas for the same reason.