Guy Cohen starred in one of the most famous music videos of the late Nineties, and lately he's been back with the band onstage Back in 1998, before social media and smartphones, MTV music videos remained a hugely influential cultural reflector for young folks, promoting imagery and sounds as dynamic as they were diverse. Boy bands were bigger than ever, Will Smith was getting jiggy with it, and Green Day were having the time of their life. Meanwhile, another California band with punk roots, the Offspring , were building their own fervent fanbase by turning catchy, bratty ditties into high-production clips that nobody ever flipped past on the remote.…