The Weekend's Viewing: Downton Abbey, Sun, ITV1 Prohibition, Fri, PBS The Blues, Sat, PBS Special When Lit, Sat, PBS

"Will someone please tell me what's going on... or have we all stepped through the looking glass?" said the Dowager Countess in Downton Abbey.

We all know how you feel, Lady Violet, because things have been moving at breakneck speed in the last few episodes, possibly literally so in the case of Vera, Mr Bates's termagant wife, whose mysterious death saw him clapped in handcuffs just before the final credits rolled. At the same time, Lord Grantham has been trembling on the brink of sexual indiscretion with a housemaid, despite having been the very soul of rectitude for the previous 12 episodes, and Matthew has made a miraculous recovery from his spinal paralysis.

In fact, you can barely make a cup of tea while Downton is on without finding that a major plot development has occurred while you were switching the kettle on. But the puzzle Lady Violet was most concerned with last night was the sudden appearance of Branson the chauffeur in the drawing room, out of uniform and in an unmistakably bolshie mood. We knew, as she didn't, that he and Sybil had just announced their plan to marry, but the Dowager soon caught up. As you can imagine, she didn't approve: "This sort of thing is all very well in novels, but in reality it can prove very uncomfortable."

Julian Fellowes had more housework on his hands than one of Downton's tweenies here, but he had one thing in his favour. Spanish flu had struck the house, an ailment that simultaneously provided narrative tension and a convenient rug under which to sweep any characters who have now become superfluous. The doctor helpfully alerted us to the disease's capricious nature, just in case we got complacent about anyone showing early signs of recovery: "It's a strange disease with sudden savage changes," he explained as Lavinia began to look distinctly peaky again. Also bedridden were Carson, Lady Cora and Mr Molesley, though the latter's sweaty pallor turned out to be down to an over-enthusiastic sampling of the dinner wines rather than viral assault. I'll confess I called it wrong. I thought that Lady Cora was going to peg out, particularly after she began to leak blood from her nose. But in the end, it was Lavinia whose funeral everybody had to attend.

If you'd thought this would clear the way for Matthew and Lady Mary, you reckoned without Fellowes's wilful habit of knocking down one hurdle only to erect a higher one a few yards down the track. So, Vera's death finally made it possible for Bates and Anna to marry, but also ensures that they won't be enjoying it for a while yet. And Matthew is so stricken by guilt (Lavinia spotted him kissing Lady Mary, and died with the words "It's better this way") that even though he's now free to follow his heart, he won't. "We're cursed, you and I, and there's nothing to be done about it," he told Lady Mary. I would guess there's at least another eight episodes to be done about it myself, and the fact that Lady Violet was last heard gamely trying to talk up the chauffeur's social connections and political ambitions suggests Julian Fellowes is already thinking about what else will go into them.

After an early sampling of PBS programming (now available to some British viewers on cable and satellite), you could be forgiven for thinking that the acronym stands for Portentous Broadcasting Service. There's a certain earnestness about serious American documentaries that may strike a British viewer as a tiny bit stodgy. While being full of good things, Ken Burns's Prohibition and the first of Martin Scorsese's series The Blues (Wim Wenders's odd compound of performance, interview and mocked-up archive) didn't exactly buck that judgement. But Special When Lit, an elegy for the American pinball machine, was a lovely thing, full of the pathos of remembered childhood and superceded technology. My flipper fingers were twitching by the end.