The playful setting of Mary Zimmerman’s La Sonnambula is that infinitesimal, magical switch from rehearsal to artistic reality… Or rather, that is what was intended. Controversial and thoroughly confusing, this production was notoriously booed on its opening night. The critics dismissed Ms Zimmerman’s production concept as alternatively tired or incoherently executed (or both); the audience felt distracted and disorientated by the constant stage business; and the conductor, Evelino Pidò, was castigated by some as “too halting” (though praised by others as “supportive of his singers” – which just goes to show you can’t please all the people all of the time). Despite all the baggage, the chance to hear Natalie Dessay and Juan Diego Flórez singing Bellini’s exquisite music still makes this well worth a watch online, not least because Bellini’s charmingly fragile work is increasingly difficult to stage – whatever the concept – for a modern audience.

The infamous staging here, then, brings us into the heart of fashionable New York: a light and airy loft-like rehearsal space, into which Ms Dessay glides in full diva mode (huddled in a delicious, outsize coat, locked to her mobile phone) to join rehearsals for La Sonnambula. Ms Zimmerman’s aim seems to have been for the line between life and performance to become translucent as the rehearsal and action take shape together. What we actually get is a jilting series of flicks between the two, which make progressively less mutual sense. However, the setting does allow for some amusing theatre stereotypes, amongst which a stroppy director and some gossipy chorus members stand out; and there’s also the opportunity to show the physicality (and occasional listlessness) of the rehearsal process, which works well too. In other words, there’s much to enjoy, even if it doesn’t quite cohere: even the more “gimmicky” (so said the Financial Times) stage moments, such as the chorus’ trashing of the rehearsal room at the end of Act I, are delivered with such enthusiasm and gleeful energy that it’s hard not to enjoy them in the moment, even if you find yourself questioning them afterwards. Above all, getting to see Ms Dessay and Mr Flórez at such close quarters rewards leniency in almost every other direction.

Mr Flórez is charming as Elvino: passionately loving, bitterly jealous, childishly sulky. His film-star presence causes obvious ripples amongst the village/theatre company (we are never quite certain), while the strength and reach of his top notes is truly impressive, even on a tiny laptop screen. In his duet with Amina, “Son geloso del zeffiro errante”, his tenderness and devotion as a lover were palpable. Ms Dessay, meanwhile, brings a pleasing physicality to Amina; it’s not a comic role, but she manages to add a few idiosyncratic comic touches which lift the action without distracting, while at all times displaying haunting vulnerability through her music. The delicacy and suppleness of her voice, particularly at the lower end of her register, give Bellini’s music an ineffable softness which is hard to resist. Her first entrance while sleepwalking, through the audience and lit by a single spotlight, was rightly celebrated, although one feels it was something a camera angle (even a series of camera angles) can’t quite recreate fully. But we can imagine. And being so close for her spellbinding “Ah! non credea mirarti” certainly makes up for it.

Mr Pidò may not have rushed his orchestra, but he gains good performances from all his singers: Jennifer Black is an alluring if desperate Lisa, Michele Pertusi a thrillingly low-voiced Count, Jane Bunnell a very unassuming Teresa – who has a sudden, unexpected moment of power when she prevents Elvino’s rash marriage to Lisa – and the chorus make the most of their flamboyant set pieces wherever possible. Musically, it is an engaging and romantic success.

It is more than tempting to imagine what this cast might have been like in a traditional production: even through this fractured setting, the performances still shine with emotion. Like a sleepwalker’s dream, La Sonnambula gets oddly muddled, doesn’t always make sense, but still has some ravishingly memorable moments.