Frankie Valli has left fans concerned again as a new video went viral of the Four Seasons star looking frail during a performance of Bye, Bye, Baby (Baby Goodbye). He originally sparked worry last year, when videos of his recent concerts circulated online – but spoke out to deny claims of elder abuse.

The singer, now 90 years old, has been pictured wearing a green sequinned jacket, a crisp black shirt and matching trousers as he held a microphone in one hand. Surrounded by backing singers…