This is the video I remember seeing, showing (I assume) Stout being served by decanting into jugs. And then, shuffled from glass to glass, which was a process described as the excuse for swapping to nitrogen pressure by Guinness themselves.
Based on this video, serving draught this way was a real palaver. It looks like there was only the highly-conditioned beer. All the messing around being needed to be able to fill a glass with beer.