This particular spoof episode of the 1970s British children's show "Rainbow" is real (not over-dubbed, like so much of such similar material on YouTube), but it never went on air for the public. It was made as an inside joke at Thames TV, for a company holiday party, and only made it onto the extra-small screen for our enjoyment in the last couple of years. BTW, we're totally going to start saying "twanger" now.