The smiling Russian prima donna onscreen tells us she feeds her son kasha - a sort of porridge - every day, before turning up to work at the New York Metropolitan Opera. Dripping pearls and rubies in a low-cut corset, Anna Netrebko chats to us mere minutes before playing the title role in the Met's season-opening opera, Donizetti's Anna Bolena.

I was sceptical about watching stage onscreen in the "Met Live on HD" series, now shown in more than 50 countries. But unlike movie pirates, the Met doesn't just set up a camera in the fourth row and leave it running.

In fact, from my comfortable position as one of only 14 viewers in a Newmarket Rialto cinema, the cameras in Netrebko's dressing room feel rather intrusive. But the woman about to play Anne Boleyn doesn't mind a jot.

She winks as she recommends The Tudors. She talks impishly to her Moscow fans in Russian: "Don't fall asleep, my dears. We work a little, we sing a little and then I get my head chopped off."

After the overture, we see Netrebko onstage. She looks regal, and is singing beautifully about internalising a really complicated situation in her head.

But I keep thinking about her making porridge and watching The Tudors. Not that those thoughts ruined my screen-opera experience. On the contrary, letting us backstage is a shrewd move, because the screen can never recreate the immersive atmosphere of really "being there". So the Met sensibly offers a completely different experience: interesting close-ups, panning cameras and informative interviews with the production team.

As the retired gentleman from Tauranga sitting next to me exulted: "I get to see the machine."

So: watching a Russian soprano in New York performing an Italian opera about English royalty while you're in New Zealand is like watching sports television with its replays and action close-ups rather than going to the game. (Ildar Abdrazakov as Henry VIII even looked like Piri Weepu, once he got all angry and unstoppable.)

It's opera seen like never before - but it's still designed to be seen live. One of opera's signature features, the grand spectacle, is missing.

Even the big screen doesn't do justice to the multitudes of chorus members.

The pros and cons are the same with London's National Theatre onscreen - which, like the Met, beams "almost live" (weeks afterwards) from an Anglophone cultural capital to the Bridgeway and Rialto cinemas.

Playing now is a production of The Kitchen, known for its group synchronisation, but this is only hinted at in tightly cropped shots. Still, the acting is a revelation.

At $33 for the Met and $25 for the National Theatre, it's steep, and the screening times are mostly friendly only to pensioners. The high prices are apparently because of the long running times - Wagner's Gotterdammerung, playing next year, is nearly six-and-a-half hours long. But when the cinemas are almost empty, and student tickets to the NBR New Zealand Opera are $8 less than student tickets to Met screenings, the profit maths doesn't seem right.

So: I arrived sceptical, I enjoyed myself more than I thought I would and it's worth checking out the season bills for the Met (next up: Don Giovanni) and National Theatre. Just in case there's something or someone you'd rather see instead of two arthouse movies or one real live small play. Unlikely in my case, but not impossible.