That was never broadcast (although it was broadcast more recently in a show of funny/rude tv moments). The story behind that clip is that every year in the late 70's/early 80's, the VT editors used to compile out-takes videos. These videos weren't for broadcast, just for their own personal entertainment. Every year the videos got more elaborate and they started filming specially scripted rude scenes using any spare studio time they had left over. They're known as "Xmas tapes" since they were made to be shown at the VT engineers Xmas parties. In the early 80's in a BBC Xmas tape they included an interview with Princess Anne which was edited to make it sound rude, and a newspaper got hold of a copy of the tape and made a front page story out of it. After that the BBC banned them from making the videos, although other channels (The Rainbow one is from ITV) carried on making them for a few years.