The clips from "Blue Peter" look 1990s to me. The footage is interspersed with various test patterns, some of which cause a moiré effect on the screen. No idea of date, sorry
I remember spending a night at my friend and her then boyfriends flat 1994/1995. I got very drunk but i switched on the TV in the middle of the night on BBC2 to see venetian blind effect colour bars and some very random tests (not DX it was perfectly clear). I'd say it was around this time.
