N obody ever came out of a performance of Wozzeck thinking that what it really needed was an extra layer to make it even more harrowing. Caution against excess, however, is not a feature of the Southbank’s Multitudes festival – gloriously so. Searing playing and singing from the London Philharmonic and a first-rate cast, conducted by Edward Gardner, combined here with Ilya Shagalov’s video art, co-created with Nina Guseva, to make Berg’s opera yet more adrenaline-inducing than ever. Shagalov’s film, on a big screen behind the players, told Wozzeck’s story in thousands of still photos. The time was today, the place a grey city, and Wozzeck part of the invisible workforce hidden by their hi-vis vests. With a translation of the sung German at the bottom, the images sped by or turned over more slowly, always as stills – except only for the moment after Marie’s murder, when the orchestra joined in a terrifying crescendo on a single note.…